SCIENCE BRINGS NATIONS TOGETHER XXVIth International Baldin Seminar on High Energy Physics Problems "Relativistic Nuclear Physics and Quantum Chromodynamics"

15 Sept 2025, 09:00 → 20 Sept 2025, 15:00 Europe/Moscow

VBLHEP JINR

The XXVIth International Baldin Seminar on High Energy Physics Problems "Relativistic Nuclear Physics and Quantum Chromodynamics", organized by the Joint Institute for Nuclear Research, will be held from September 15 to 20, 2025 in Dubna, Russia.

The Seminar continues the series of traditional meetings that was established by him. Among conferences that were organized by Alexander Mikhailovich Baldin (1926–2001) of special importance is just this series of the International Seminars on High-Energy Physics Problems started in 1969 with the support of M.A. Markov (1908-1994). They have been given an unofficial, somewhat witty, name "Baldin autumn".

The program is supposed to present reports from major experimental collaborations and summaries of major theoretical and experimental advances made in relativistic nuclear physics.

The Seminar programme will consist of review talks and contributions presenting original researches. The working language of the Seminar is English.

The Seminar will be "in person".

Bulletin_First.pdf

Bulletin_Second.pdf

Dubna map

Poster.pdf

Programme-final.pdf

VBLHEPMap.pdf

Monday 15 September

09:00 → 10:00 Registration

10:00 → 10:55 Plenary

Convener: Malakhov, Aleksandr (JINR)

10:00 Opening

Speaker: Matveev, Victor (Joint Institute for Nuclear Research)

1.В.А. Матвеев_Открытие XXVI конференции_15.09.2025.pdf

10:15 Heavy ions in science and technology

Speaker: Oganessian, Yuri (FLNR, JINR)

2.ЛВЭ_Балдин_2025_о_Совете_РАН.pdf

10:55 → 11:30 Group photo, Coffee break

11:30 → 12:30 Plenary

Convener: Taranenko, Arkadiy (VBLHEP JINR)

11:30 Status and perspectives of the MPD at NICA

The main objective of the Multi-Purpose Detector (MPD) at NICA is to study the structure of the QCD phase diagram at finite temperatures and high baryochemical potentials. To reach this goal, the MPD will study heavy-ion collisions in a wide energy range 2.4-11 GeV. By measuring a wide range of signals from heavy-ion collisions, the MPD will investigate various physics phenomena, including the equation of state and critical behavior of the QCD matter, properties of in-medium hadron spectral function, the characteristics of hyperon-nucleon interactions, etc.
In this report, we will review the status of the MPD facility and its physics program, with a focus on the first expected measurements to be performed for Bi+Bi and Xe+W collisions in collider and fixed-target configurations, respectively.

Speaker: Dr Riabov, Victor (PNPI)

RiabovV_MPD_Baldin2025.pdf

12:00 Status of BM@N experiment

Zavertyaev M. , on behalf of the BM@N Collaboration

The BM@N experiment is the first fixed-target experiment operated at
NICA accelerating complex, JINR, Dubna.
The BM@N experiment collected data on carbon, argon and xenon beams
with different solid targets within the energy range $\sqrt{s_{NN}} = 2.3-3.5GeV$.

Review of first physics results on pion, proton, deuteron, triton,
strange particle and hyper nucleous production are presented.
Results are compared with theoretical models predictions and with the
existing experimental data.

Plans for a future activity are discussed.

Speaker: Zavertyaev, Mikhail (P.N.Lebedev Physical Institute, RAS)

4.Talk_zavertyaev.15.09.2025.pdf

12:30 → 14:00 Break

14:00 → 15:40 Quantum chromodynamics at large distances

Convener: Dzhunushaliev, Vladimir (al-Farabi KazNU)

14:00 Exploring Higher-Twist Hadron Structure in Light-Front QCD

Understanding the internal structure of hadrons beyond the leading-twist approximation is essential for probing the non-perturbative dynamics of QCD. While high-$Q^2$ processes are dominated by gluon and sea quark dynamics, the low-$Q^2$ region requires non-perturbative modeling to capture the role of valence quarks and confinement. To address this, I investigate a wide range of distribution functions up to twist-4 within the light-front quark-diquark model (LFQDM).

I present a detailed analysis of higher-twist TMDs, emphasizing model-dependent predictions and structural relations. A complete set of linear, quadratic, and inequality relations is derived at both intra-twist and inter-twist levels. A helicity-based parameterization framework is introduced, along with a classification table that allows the identification of spin-$1/2$ TMDs by parton and parent helicities. Model-specific amplitude matrices for each diquark configuration are also constructed. The results are compared with other models (e.g., LFCQM, bag model) and CLAS data.

Additionally, I report the first model calculations of higher-twist chiral-even GPDs at zero skewness for the proton, along with their spatial distributions. Results on higher-twist GTMDs at zero skewness are also discussed. Preliminary findings for pion and kaon GTMDs are presented as a step toward extending the analysis to mesonic systems.

The results are most relevant at low-to-moderate scales ($Q \sim 1$-$3~\mathrm{GeV}$, $\sqrt{s} \sim 10$-$30~\mathrm{GeV}$), where higher-twist effects are enhanced. These results can be beneficial for facilities operating in this energy region, such as SPD at NICA, COMPASS, and JLab, by providing input for parametrizations of twist-3 and twist-4 distributions. While evolution equations for these functions remain incomplete, modeling them at low scales remains essential for interpreting data and guiding future theoretical developments.

Speaker: Dr SHARMA, SHUBHAM (Moscow Institute of Physics and Technology (MIPT), Dolgoprudny 141700, Russia)

Talk ISHEPP 2025 v10.pdf

14:30 Phase diagram of QCD and two color QCD: dualities and inhomogeneous phases

It has been shown in the framework of effective models that QCD phase diagram as in thee color case as well as in two color one possesses dualities.
It means that various phenomena are dual with respect to each other. Then dualities were shown in a more and more general setings. And then finally dualities has been shown from first principles,
three dualities as in two color QCD and one in three color one. The fact that dualities have been shown from first principles, i. e. in QCD itself, expanded their possible application much further.
In the talk I discuss two interesting applications. Studies of speed of sound at various chemical potentials. And studies of inhomogeneous phases, including rather unexpected ones. Inhomogeneous phases has long history on research but it is still open question if there is inhomogeneous phases in QCD at finite baryon chemical potential. Some inhomogeneous phases have been predicted in various approaches. Dualities gives us opportunity to predict plethora of new inhomogeneous phases. The most interesting phase is the one at zero baryon chemical potential, as a rule one is used to the fact that inhomogeneous phases can be present at nno-zeroi mu_B and it is a first example of inhomogeneus phase at zero mu_B (some other chemical potentials are non-zero)

The talk is partly based on

Eur. Phys. J. C 84 (2024), 1140
Phys. Rev. D 111 (2025) no.1, 014021

Speaker: Zhokhov, Roman (IHEP, IZMIRAN)

Pres Baldin.pdf

14:50 Chiral and deconfinement crossovers at finite quark spin density from lattice QCD

We study the effect of finite spin quark density on the chiral and deconfinement thermal crossovers using numerical simulations of lattice QCD with two dynamical light quarks. The finite spin density is introduced by the quark spin potential in the canonical formulation of the spin operator. We show that both chiral and deconfinement temperatures are decreasing functions of the spin potential. We determine the parabolic curvatures of crossover temperatures in a limit of physical quark masses.

Speaker: Dr Roenko, Artem (BLTP, JINR)

roenko_Baldin_seminar_2025.pdf

15:20 The light-by-light contribution to the anomalous magnetic moment of muon within the nonlocal chiral quark model with vector and axial-vector meson

The hadronic light-by-light (HLbL) contribution to the muon anomalous magnetic moment is calculated within a nonlocal quark model incorporating scalar--pseudoscalar and vector--axial-vector interactions.
Both resonance contributions and contact terms are included in the calculation.

For the non-strange quark loop, the obtained contribution is
$ a_{\mu}^{\mathrm{HLbL,\,Loop}} = (93 \pm 9.9) \times 10^{-11}. $
The total HLbL contribution, accounting for meson exchanges and strange quark effects, is
$ a_{\mu}^{\mathrm{HLbL}} = (154 \pm 12.4) \times 10^{-11}. $

When combined with other contributions, our result shows good agreement with recent experimental data.

Speaker: Radzhabov, Andrey (Institute for System Dynamics and Control Theory SB RAS)

RadzhabovBaldin25NewCut.pdf

14:00 → 15:40 Relativistic heavy ion collisions

Convener: Mamaev, Mikhail (NRNU MEPhI)

14:00 Collective behavior of hyperons in Pb-Pb collisions with ALICE

Hyperons created in non-central nucleus-nucleus collisions possess collective behavior known as elliptic flow (v2). Also, hyperons are sensitive to the magnetic field and vorticity of the produced system resulting in their polarization. The measurement of elliptic flow and the polarization of Lambda and Xi hyperons in Pb--Pb collisions, performed with the ALICE detector at the LHC are presented. In addition, the expected results on the polarization measurement of Lambda and Xi hyperons with the high statistics collected in Pb--Pb collisions by ALICE during the Run 3 of the LHC, will be shown.

Speaker: Dr Borissov, Alexander (JINR)

ABorissov-BaldinConf-15sep25.pdf

14:20 Production of $\overline{\Sigma}^{\pm}$ baryons in p--Pb and pp collisions at the LHC with ALICE

The enhancement of strangeness production has long been considered as a signature of quark–gluon plasma (QGP) formation in heavy-ion collisions. While extensive measurements have refined this idea over time, $\Sigma$ hyperons remain experimentally unexplored at the LHC energies. In this study, we present the first measurements of the transverse momentum ($p_{\mathrm{T}}$) spectra and integrated yields of $\overline{\Sigma}^{\pm}$ hyperons in pp and p–Pb collisions at $\sqrt{s_{\mathrm{NN}}} = 5.02$ TeV using the ALICE detector. The analysis leverages the previously unexplored decay channel $\overline{\Sigma}^{\pm} \rightarrow \overline{n}\pi^{\pm}$, employing a novel method for antineutron reconstruction with the PHOS electromagnetic spectrometer.

The $\overline{\Sigma}^{\pm}$ $p_{\mathrm{T}}$ spectra, measured in the range $0.5 < p_{\mathrm{T}} < 3$ GeV/$c$, are compared with predictions from PYTHIA 8, DPMJET, PHOJET, EPOS LHC, and EPOS4. Among these, EPOS LHC and EPOS4 provide the best agreement with the data in both collision systems, while models neglecting multiparton interactions exhibit significant discrepancies at high $p_{\mathrm{T}}$. The total yields of $\overline{\Sigma}^{\pm}$ are also compared with Thermal-FIST and dynamical model predictions, all of which reproduce the measured yields within uncertainties.

Additionally, the nuclear modification factors ($R_{\mathrm{pPb}}$) for $\overline{\Sigma}^{+}$ and $\overline{\Sigma}^{-}$ are evaluated and compared with those of protons, $\Lambda$, and $\Xi$ hyperons, as well as EPOS LHC and EPOS4 predictions. No significant deviations from model expectations or other hadron measurements are observed, supporting consistency with current theoretical frameworks.

Speaker: Gordeev, Pavel

Sigma_Pavel_Gordeev.pdf

14:40 Vector mesons photoproduction in ultra-peripheral ion-ion collisions

The main goal in investigation of vector mesons production in
ultra-peripherall collisions (UPC) of relativistic ions is the possibility to constrain the nuclear and proton gluon distributions.
The strong electromagnetic fields accompanying heavy ions accelerated
at BNL or LHC may lead to huge vector mesons photoproduction in
ultra-peripheral collisions, where there is no overlap between the
colliding nuclei. Such experiments have been done in the last decade by STAR and ALICE collaborations.
From another hand considerable interest could be to study of vector mesons in UPC at future collider NICA with
the center-of-mass energies 5-11 GeV the region of Vector Meson Dominance
model. The possible performance of such investigations at NICA is under the way.
We point out a significance of ultra-peripheral photoproduction of vector mesons in the Coulomb field of nuclei as a means of measuring
the radius of the neutral vector meson . This contribution to the production amplitude is small compared to the conventional
diffractive amplitude, but because of large impact parameters inherent to the ultra-peripheral Coulomb mechanism its impact on
the diffraction slope is substantial. We predict appreciable
and strongly energy dependent increase of the diffraction slope towards
very small momentum transfer.The magnitude of the effect is proportional to
the mean radius squared of the vector meson and is within the reach of
high precision experiments in ultra-peripheral heavy ions collisions , which gives a unique experimental handle on the size of vector mesons.

Speaker: Gevorgyan, Sergey (JINR)

Gevorgyam.pdf

15:00 MPD-ITS Current status

D mesons and the λ baryon are currently considered as one of the most perspective probes for search of quark de-confinement of the matter during its transition from a state of hadron gas to quark-gluon plasma. The tracking system of the MPD experiment at NICA collider will include the vertex silicon detector MPD-ITS designed for the efficient registration of these short-lived products of nuclear-nuclear interactions, to be built using Monolithic Active Pixel Sensors (MAPS) based on the MICA chip that is being developed in the framework of a dedicated Consortium that was born from the long-lasting collaboration between JINR and Chinese institutions lead by the Central China Normal University (Wuhan). The second prototype of such a chip is expected to be received at JINR in 2025. The present status of the MPD-ITS project is reported here.

Speaker: Tsapulina, Ekaterina (JINR)

XXVIth_International_Baldin_Seminar2025_MPD_ITS_Tsapulina_v1.pdf

XXVIth_International_Baldin_Seminar2025_MPD_ITS_Tsapulina_v1.pptx

15:20 Two-particle rapidity correlations in strongly intensive quantities within string model

Studies of the phase diagram of strongly interacting matter created in nuclear collisions are typically carried out using event-by-event fluctuations. The strongly intensive quantities form a family of promising observables that are free from trivial volume fluctuations. In the case of multiplicity fluctuations over separate rapidity intervals, the behavior of the corresponding strongly intensive quantity is analyzed using the color string approach. At short distances, it is mostly sensitive to the details of two-particle correlations due to string fragmentation. Conversely, long-range effects are dictated by collective interactions between strings.

In this report we model these two phenomena by the simulated annealing algorithm and string fusion. We present how interplay between short-range and long-range correlations breaks the property of strong intensity.

The author acknowledges Saint-Petersburg State University for a research project 103821868.

Speaker: Andronov, Evgeny (Saint Petersburg State University)

baldin_andronov_2025.pdf

15:40 → 16:00 Coffee break

16:00 → 18:10 Quantum chromodynamics at large distances

Convener: Radzhabov, Andrey (Institute for System Dynamics and Control Theory SB RAS)

16:00 Gluodynamics in accelerated frames using lattice simulation

We investigate the properties of SU(3) gluon plasma at high temperature under acceleration using lattice simulations in Rindler spacetime. Our results reveal a spatial crossover transition from confinement to deconfinement opposite to the direction of acceleration, consistent with the Tolman-Ehrenfest (TE) law. Using this law, we renormalize the Polyakov loop in Rindler space. Additionally, we observe that the transition width and peak diminish as acceleration increases.

Speaker: Day, Jayanta (BLTP JINR)

presentation_JD.pdf

16:20 Studying properties of the SU(2) QCD by lattice field theory methods

SU(2) QCD have previously been extensively studied and it was found, that qualitatively it possesses similar properties to it's real version with SU(3) color gauge group. Some of those properties, confinement-deconfinement transition and chiral symmetry restoration, are of a great interest. Thus, studying it's properties may help in understanding those of a real QCD. In addition, SU(2) QCD has a very useful property, which allows to simulate it using lattice field theory methods at a non-zero baryon density directly, which makes it interesting for studying.

Speaker: Kudrov, Ilya (IHEP, protvino)

Studying_properties_of_the_SU_2__QCD_by_lattice_field_theory_methods_Dubna_2025.pdf

16:40 New analysis of the Bjorken sum rule based on the analytic perturbation theory

We extend our theoretical study of the Bjorken sum rule for polarized DIS by building on recent Jefferson Lab data for the nucleon spin structure in the infrared region of small transferred momenta $Q^2<1$ GeV$^2$, where the higher order perturbative corrections and higher-twist contributions play a significant role.
Our theoretical approach is based on the analytic perturbation theory and an original method for matching regions with large and low $Q^2$ values.
By fixing the QCD parameters at large $Q^2$, we move into the region of low $Q^2$, while using the Gerasimov—Drell—Hearn sum rule as a boundary condition.
We investigate the stability of our theoretical predictions and
the agreement between the theoretical description and the experimental data for values of $Q^2$ very close to zero.

Speaker: Volkova, Daria

Volkova_2025_Baldin ISHEPP.pdf

17:00 Contribution of linearly polarized gluons in charmonium production within the Soft Gluon Resummation approach

The TMD factorization is a consistent framework to describe hadron processes at small transverse momenta [1], though there are several approaches for modeling TMD parton distributions. The Soft Gluon Resummation approach is such a model that allows to express TMD parton distributions via collinear ones and nonperturbative phenomenological part [2]. Evolution of perturbative part is controlled with Collins-Soper equations and can be derived as Sudakov factor [3]. Parton distributions for initial unpolarized protons can be written in terms of TMD unpolarized parton distributions and Boer-Mulders functions that refer to linearly polarized partons in unpolarized nucleons [4]. Charmonium production in proton-proton collisions is an appropriate process to estimate these contributions. Contribution of unpolarized parton distributions have already been investigated in Refs. [5, 6] and now we focus on linearly polarized gluons and report on $J/\psi$ and $\eta_c^{}$ production at $p_T^{} \ll M$ with $M$ as a mass of charmonium, for $\sqrt{s} \leqslant 200$ GeV, including 27 GeV for the forthcoming experiments of SPD NICA. Hadronization of produced quarks into charmonium is considered within the NRQCD framework [7].

References:
[1] J. C. Collins, Foundations of Perturbative QCD (2011).
[2] J. Bor, D. Boer, Phys. Rev. D 106 (2022) 1, 014030.
[3] J. C. Collins, D. E. Soper, Nucl. Phys. B 193 (1981) 381.
[4] P. J. Mulders, J. Rodrigues, Phys. Rev. D 63 (2001) 094021.
[5] V. A. Saleev, K. K. Shilyaev, Phys. Atom. Nucl. 88 (2025) 2, 338-341.
[6] V. A. Saleev, K. K. Shilyaev, arXiv:2502.16461 [hep-ph] (2025).
[7] G. T. Bodwin, E. Braaten, G. P. Lepage, Phys. Rev. D 51 (1995) 1125-1171.

Speaker: Shilyaev, Kirill

Report_Shilyaev.pdf

17:20 Color field configuration between three static quarks

Within Yang-Mills-Proca theory with external sources, regular, finite energy solutions are obtained. It is shown that color electric/magnetic fields have two components: the first part is a gradient/curl component,
respectively, and the second part is a nonlinear component. It is shown that the color electric field has an Y-like spatial distribution.
Such an Y-like behavior arises because the gradient component of the electric field is present. The nonlinear component of the electric field is a curl one, and it appears because the vector potential sourced by a solenoidal current is present. The color magnetic field is purely curl one, since its nonzero color components do not contain a nonlinear component; this results in the fact that its force lines lie on the surface of a torus. It is shown that the results obtained are in good agreement with the results obtained in lattice calculations in quantum chromodynamics. To discuss such an agreement, we consider a procedure of nonperturbative quantization and discuss possible approximations ensuring such an agreement. Also, we compare the energy profiles obtained by us with those obtained in lattice calculations with a static potential.

Speaker: Prof. Dzhunushaliev, Vladimir (al-Farabi KazNU)

three_quarks_conf.pdf

17:40 Light quark masses

The bounds on the light quark masses are obtained by fitting the squares of pseudoscalar meson masses $m^2_\pi$ and $m^2_K$ to second order in $1/N_c$ expansion. It is shown that the values of the quark mass ratios $x=m_u/m_d$ and $y=m_s/m_d$ belong to the third order algebraic curve $f(x,y)=0$. Two parameters of the curve are fractional linear functions of the squared masses of $\pi$ and $K$ mesons and, when Dashen's theorem is satisfied, coincide with the values $x_W=0.56$ and $y_W=20.18$ obtained by Weinberg from the current algebra. The curve is stable, i.e. it does not change when taking into account chiral corrections in the mass formulas of pseudoscalars, and is universal: any two independent fractional linear functions lead to the same curve. A part of the curve corresponding to the physical values of the quark masses can be distinguished if we use the ratio $m_s/m_{ud}=27.23(10)$ known from calculations on the lattice, which gives $m_u/m_d=0.455(8)$, $m_s/m_d=19.81(10)$. The value of the low-energy constant $B_0(2\, GeV)=2.682(36)(39)\,GeV$ (also known from lattice simulations) allows us to obtain absolute values of the light quark masses: $m_u=2.14(7)\, MeV$, $m_d=4.70(12)\, MeV$, $m_s=93.13(2.25)\, MeV$ (all values refer to the $\overline{MS}$ scheme at the $2\, GeV$ scale).

Speaker: Osipov, Alexander (JINR)

Osipov.pdf

16:00 → 18:10 Relativistic heavy ion collisions

Convener: Riabov, Viktor (NRC "Kurchatov Institute" PNPI)

16:00 Directed flow of protons in Xe+CsI collisions at the beam energy of 3.8A GeV with BM@N

In the collisions of heavy ions at the beam energy of 3.8A GeV dense baryonic matter is produced within the overlap region of colliding nuclei. The azimuthal anisotropy of produced in the collision particles is a sensitive probe of the properties of the dense baryonic environment. We present the preliminary results for the first coefficient of the Fourier decomposition of azimuthal distribution (directed flow) of protons produced in Xe+CsI reaction at the beam energy of 3.8A GeV, collected by the BM@N experiment in the early 2023. We compare the obtained values for the directed flow of protons with the existing world data and discuss their application for further restricting the Equation of State for dense baryonic matter.

Speaker: Mamaev, Mikhail (NRNU MEPhI)

Baldin_2025_Mamaev.pdf

16:20 Impact of in-medium on proton scattering amplitude at incident energies 12.7-1000 MeV

The effect of nuclear medium on proton-nucleus scattering amplitude is investigated by analyzing experimental differential cross sections of proton elastic scattering on $^{90}$Zr at a very wide range of incident energies from 12.7 to 1000 MeV using the microscopic model of proton–nucleus optical potential. This effect has a major impact on the proton-nucleon cross section, σ, the most physically significant parameter of the interaction potential. The in-medium parameter σ, which effectively replicated experimental data at low incident energies, is significantly smaller than the proton-nucleon cross section when they scatter in free space. At high incident energies, however, the two σ values are fairly similar to one another.

Speaker: Abdulmagead, Ibrahim (Joint Institute of Nuclear Research, Dubna, Russia)

my Baldin 2025 presentation.pdf

16:40 Pion Spectra and Entropy per Rapidity in Au–Au Collisions at NICA Energies Using HRG with Resonance Decays and Tsallis Distribution

We investigate the transverse momentum spectra and entropy per unit rapidity of charged pions produced in central Au--Au collisions at $\sqrt{s_{NN}} = 7.7$ and $11.5$~GeV, relevant for the NICA energy domain. The low-$p_T$ region is fitted using a Tsallis distribution, while the intermediate-to-high $p_T$ tail is described by a hadron resonance gas (HRG) model incorporating resonance decay contributions. A smooth transition point is chosen to ensure continuity between the two models. The combined fits are employed to extrapolate the measured spectra toward $p_T = 0$ and high $p_T$ regions, enabling a reliable estimation of the entropy density per rapidity. Our analysis shows that the hybrid Tsallis+HRG approach captures the pion spectra across the full $p_T$ range with good precision. The extracted entropy values serve as important thermodynamic observables in the study of strongly interacting matter at high baryon density.

Speaker: Dr Nasar, Mahmoud (Physics Department, Faculty of Science, Benha University, 13518, Benha, Egypt, and Academy of Scientific Research and Technology (ASRT), 101 Kasr Al Aini Street, 11516, Cairo, Egypt)

Nasar_Aish_Conference_Presentation_FINAL.pptx

17:00 Performance for inclusive photon and neutral pion spectra and anisotropic flow measurements with the MPD experiment

Direct photons produced in electromagnetic processes in heavy ion collisions do not interact with other particles in the collision zone. Analysis of direct photon spectra and anisotropic flow could provide additional information on the conditions at the production time and on the development of collective flow. Spectra and flow of direct photons are quantified based on the corresponding observables for inclusive photons and neutral pions, the main source of decay photons. Moreover, results for neutral pions may help to constrain properties of hot and dense nuclear matter thanks to robust particle identification and wide coverage in transverse momentum.
We present the performance for inclusive photon and neutral pion spectra and anisotropic flow measurements with the MPD experiment in both collider and fixed-target regimes. The study was done using simulations of detector response to particles produced by the UrQMD event generator with realistic algorithms of event reconstruction and analysis. Different methods for photon and neutral pion reconstruction are considered to estimate possible systematic biases.

Speaker: Golosov, Oleg (NRC "Kurchatov Institute", MEPhI)

Golosov_MPD_flow.pdf

17:30 Hadronic resonance production with ALICE at the LHC

Recent results on short-lived hadronic resonances obtained with the ALICE at LHC energies are presented.
These results include masses, widths, transverse momentum spectra,
yields and the ratios of resonance yields to those of longer-lived particles, and elliptic flows.
Results will be compared with model predictions and measurements at lower energies.

Speaker: Kiselev, Sergey (NRC «Kurchatov Institute»)

Baldin2025-Kiselev.pdf

17:50 Anisotropic flow in asymmetric Xe+W collisions at MPD-FXT

A key goal of beam energy scan programs with relativistic heavy-ion collisions at √sNN=2-5 GeV is probing the high-density equation of state (EoS) and possible phase transitions in dense baryonic matter. Anisotropic flow measurements provide critical insights into these properties through the final-state charged-particle azimuthal distributions. However, for the MPD experiment at NICA operating in the fixed-target mode (MPD-FXT), flow measurements face challenges in asymmetric collision systems such as Xe+W.
We present the MPD-FXT performance for the flow measurements and analyze azimuthal anisotropy in asymmetric heavy-ion collisions.

Speaker: Parfenov, Peter (JINR, NRNU MEPhI)

Baldin2025_Parfenov.pdf

Tuesday 16 September

09:00 → 10:40 Plenary

Convener: Prof. Braguta, Victor (JINR)

09:00 The atomic nucleus as a bound system of $3A$ quarks

Russian Federal Nuclear Center -- VNIIEF, Sarov, 607188 Nizhni Novgorod Region, Russia

Yukawa's meson theory of nuclear binding suffers from serious shortcomings, some of which are revealed here. To remedy the situation, it is necessary to take a closer look at the nucleus as a bound system of quarks based on an effective theory derived from quantum chromodynamics in the low-energy limit. We review some models that embody essential features of the desired effective theory. The Fermi gas model allows us to understand why the number of $d$ quarks in stable light nuclei is almost the same as the number of $u$ quarks. A modifed bag model reveals the reason for deviation from this rule about the quark composition of stable nuclei heavier than ${\rm {}^{40}_{20}Ca}$. This model describes with acceptable accuracy the static properties of a very significant part of stable isotopes. To get the most out of the modified bag model, it is advisable to resort to gauge/gravity duality. In the present context, it is appropriate to adopt a new version of duality: ``The dynamical affair inside an extremal black hole located in ${\rm AdS}_5$ is mapped onto the corresponding affair of a stable nuclear (or subnuclear) system living in ${\mathbb R}_{1,3}$''.
With this version of duality, one can predict the main decay channel of the lightest glueball. Another implication of duality is that it explanains why the periodic table contains a limited number of stable elements. It transpires that there exists a maximum allowable electric charge $Z_{\rm max}$ of stable heavy nuclei, and, moreover, duality makes it possible to calculate this quantity: $Z_{\rm max}\approx 82$.

This talk is an overview of the following papers:

1. B. P. Kosyakov, E. Yu. Popov, and M. A. Vronski.
   The bag and the string: Are they opposed?
   Phys. Lett. B 744, 28-33 (2015).

2. B. P. Kosyakov, E. Yu. Popov, and M. A. Vronski.
   Could the static properties of nuclei be deduced from the dynamics of a single quark?
   Eur. Phys. J. A 53: 82 (2017); arXiv: nucl-th/1604.06613.

3. B. P. Kosyakov, E. Yu. Popov, and M. A. Vronski.
   Correspondence between the physics of extremal black holes and that of stable heavy atomic nuclei.
   Class. Quantum Grav. 36: 135001 (2019); arXiv: hep-th/1802.03545.

4. M. A. Vronski, B. P. Kosyakov, and E. Yu. Popov.
   How to detect the lightest glueball.
   JETP 133, 154-160 (2021) [Translated from: Zh. Eksp. Teor. Fiz. 160, 188-196 (2021)]; arXiv: hep-ph/1905.09326.

5. B. P. Kosyakov, E. Yu. Popov, and M. A. Vronski.
   Why is ${}^{208}_{82}{\rm Pb}$ the heaviest stable nuclide?
   Eur. Phys. J. C 84: 807 (2024); arXiv: nucl-th/2309.13082.

Speaker: Kosyakov, Boris

1.Kosyakov-nuclei_quarks.pdf

09:30 Relativistic light-front wave function of He-3

In the framework of explicitly covariant formulation of the light-front dynamics, we calculate the relativistic He-3 wave function. It is determined by 32 spin-isospin components, each of them depends on five variables. As interaction, we take the one-meson exchange kernel as it is, without any potential approximation. At the non-relativistic relative momenta, five of these components dominate and closely resemble their non-relativistic counterparts. Relativistic effects manifest themselves in deviations in the relativistic domain of these components from the non-relativistic ones and in appearance of new components.

Speaker: Karmanov, Vladimir (Lebedev Physical Institute)

10:00 Azimuthal anisotropies from jets in pp, heavy ion collisions up to ultra cold gases

Reanalysis of the relatively old data collected by the CERES/NA45 experiment at the CERN SPS in 0–30% central PbAu collisions at $\sqrt{s_{NN}}$ = 17.3 GeV has been performed. For the first time, the measurement of the $v^{1/3}_{3}/v^{1/2}_{2}$ ratio reveals, independently of the hydrodynamic models, hydrodynamic behavior of the formed system. Recently, the CMS data have revealed long-range correlations within high-multiplicity jets in proton-proton (pp) collisions at $\sqrt{s}$ = 13 TeV, suggesting collective behavior in systems much smaller than those typical of heavy ion collisions. The Q-cumulant analysis, performed using data from a single image of the expanding ultra cold gas, shows a proper cumulant ordering among the $v_{2}$ harmonics $v_{2}\{2k\} \gtrsim v_{2}\{2(k+1)\}$ up to high order $2k$. That splitting enabled calculation of the corresponding hydro probes. Additionally, the Q-cumulant analysis has been performed in a single AuAu collision at $\sqrt{s_{NN}}$ = 200.0~GeV. Cumulant splitting in a single event has been observed for the first time.

Speaker: Milosevic, Jovan (Vinca Institute of nuclear sciences)

JMilosevic_ISHEP25.pdf

10:20 Study of $D_{03}$ and $D_{30}$ dibaryons in a SU(3) chiral constituent quark model

After the short introductions of the experimental findings of $d^*(2380)(D_{03})$ [1,2,3] and of several theoretical efforts to interpret its structure, the study of $d^*(2380)$ on the quark–gluon degrees of freedom is presented in this talk. Based on our SU(3) chiral constituent quark model, its mass, width, wave function, and partial widths of almost all possible strong decays are evaluated with the $\Delta\Delta + C_8C_8$ structure. We found that this dibaryon is strongly bounded due to the short range vector meson exchange potential. The obtained results reasonably agree with the data, which implies that the $d^*(2380)$ resonance could be assigned as a compact hexaquark system with the hidden-color component ($C_8$) being dominant. Moreover, its electromagnetic characteristics, such as the charge distribution, charge radius, multipole moment, and etc. are further calculated. Because of the sensitivity of these physical quantities to different interpretations of $d*(2380)$, some of those observables can be used as additional physical quantities to further distinguish the structures of $d^*(2380)$ [4]. In addition, its possible mirror state of $D_{30}$ structure is also studied within the same approach. Our result shows that this possible dibaryon is a weakly bounded state and it has a sizeable hidden-color component as well. By comparing the results for the two dibaryons and the model parameter sets, the effects of one gluon exchange and vector meson exchange terms in our approach are discussed [5].

[1] P.~Adlarson {\it et al.} (WASA-at-COSY Collaboration),
Evidence for a New Resonance from Polarized Neutron-Proton Scattering,
Phys.\ Rev.\ Lett.\ {\bf 112}, 202301 (2014).

[2] H. Clement,
On the History of Dibaryons and their Final Discover,
Progress in Particle and Nuclear Physics, {\bf 93}, 195 (2017).

[3] H.~Clement and T.~Skorodko,
Dibaryons: Molecular versus Compact Hexaquarks,
Chin. Phys. C \textbf{45}, 022001 (2021).

[4] Yu-Bing Dong, Peng-Nian Shen, and Zong-Ye~Zhang,
$d^*(2380)$ in a chiral constituent quark model,
Prog. Part. Nucl. Phys. \textbf{131}, 104045 (2023).

[5] Qi-Fang L{\"u}, Yu-Bing Dong, Peng-Nian Shen, and Zong-Ye Zhang,
Reveal short range interactions between u/d quarks in the NN, $D_{03}$, and $D_{30}$ systems,
arXiv: 2407.01993, Sci. China Phys. Mech. Astron. \textbf{68}, 232011 (2025).

Speaker: Dong, Yubing (Institute of High Energy Physics, Chinese Academy of Sciences, P. R. China)

DYB(2025_09_05)v4.pdf

10:40 → 11:00 Coffee break

11:00 → 12:50 Plenary

Convener: Karmanov, Vladimir (Lebedev Physical Institute)

11:00 Quark color - a step towards understanding the properties of nuclear matter (to the 60th anniversary of the colored quark hypothesis)

Speaker: Matveev, Victor (Joint Institute for Nuclear Research)

V.A. MATVEEV_Talk at BALDIN Conference.pdf

11:40 25 years of heavy-ion physics at the RHIC

The Relativistic Heavy Ion Collider (RHIC), located at Brookhaven National Laboratory,
is celebrating its 25th year of operation, making a significant contribution in nuclear physics research.
Over the past 25 years, RHIC has been instrumental in studying fundamental aspects of matter by
colliding a variety of atomic nuclei, from protons to uranium, at different energies from 3 to 200 GeV,
providing a broad spectrum of data for analysis. In this presentation I will review some of the key results
from the RHIC heavy-ion physics program.

Speaker: Taranenko, Arkadiy (VBLHEP JINR)

Baldin25TaranenkoFinal(2).pptx

12:20 Spatially inhomogeneous confinement/deconfinement phase transition in rotating gluodynamics and QCD

Quark-gluon plasma created in heavy-ion collision experiments is subjected to rapid rotation which
might modify QCD properties. In this report we are going to present the results of lattice study
on how rotation influences phase transitions in gluodynamics and QCD.
To study rotation we pass to the reference frame which rotates with the system.
In this frame the problem is reduced to study of glyodynamics in external gravitational field.
We found that in a certain temperature interval there exists spatially inhomogeneous
confinement/deconfinement phase transition.

Speaker: Prof. Braguta, Victor (JINR)

report.pdf

12:50 → 14:00 Break

14:00 → 15:40 Applied use of relativistic beams

Convener: Andronov, Evgeny (Saint Petersburg State University)

14:00 IMPORTANCE OF THE NEUTRON MODERATORS FOR NEUTRON INDUCED RELATIONS PLACED IN MASSIVE SPALLATION TARGET AND NUCLEAR FUEL IN ADS

The aim of the work is to investigate the neutron induced reactions in a massive target for ADS as a function of neutron moderators, where MCNP6 transport code is used. The ADS (Accelerator Driven System) contains three main parts: 1). Target, where the proton beam delivers its energy, 2). Nuclear fuel and cooling system, 3). Accelerator. Irradiation of the target by a relativistic proton beam generates high energy neutron flux in the central part of the target and a small part of the flux delivers its energy in the nuclear fuel. The keff of the fuel is in the range 0.9-0.95. For moderation (reflection) of the neutron flux, beryllium and lead are used. The cooling system modified the neutron flux too. The helium and liquid sodium are used as a coolant in nuclear facilities. In the work are simulated modification of high energy neutron flux in the targets and nuclear fuel in case of different cooling systems.

Speaker: Mr Gushterski, Rumen (1Institute of Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, Bulgaria, 2 Joint Institute for Nuclear Research, Dubna, Russia)

Gushterski_Zhivkov_BALDIN_2025.pdf

Gushterski_Zhivkov_BALDIN_2025.pptx

14:20 Analysis of α_S (q^2) of π^- mesons and protons from π^- C interactions at 40 GeV/c and pp interactions at 205 GeV/c

Abstract: In this paper we studied the behaveours of α_S (q^2) of π^- mesons and protons produced in π^- C interactions and pp interactions at two different incident energies. We note that in π^- C interactions are produced the secondary cumulative particles in difference from pp interactions.
In this paper we showed that with the help of the cumulative particles from π^- C interactions at 40 GeV/c we can obtain the values of α_S (q^2) at 205 GeV/c and the obtained experimental values of α_S (q^2) are in good agreement with QCD predictions.

Speaker: Mr Baatar, Otgongerel (Institute of Physics and Technology, Mongolia)

Otgongerel B presentation 16092025.pdf

14:40 Study of the running coupling constant of π- mesons and protons from p+p and p+C interactions at 10 GeV/c

We investigate the running coupling constant $\alpha_s$($q^2$) for $\pi^-$-mesons and protons produced in $p+p$ and $p+C$ interaction at 10 GeV/c. The precise determination of $\alpha_s$($q^2$) critically depends on the choice of the cut-off parameter $\Lambda_{QCD}$ in its defining expression. For this analysis, we adopt $\Lambda_{QCD} = (c \hbar) GeV = 0.197 GeV$. The resulting $\alpha_s$($q^2$) values are computed and systematically compared with the theoretical predictions of Quantum Chromodynamics (QCD).

Speaker: Khishigbuyan, Narankhuu (Institute of Physics and Technology Mongolian Academy of Sciences)

Khishigbuyan_Baldin ISHEPP XXVI_2025.pdf

15:00 Study of the running coupling constant of 𝝅− mesons and protons from 𝒑+𝒑 and 𝒑+𝑪 interactions at 4.2 𝑮𝒆𝑽/𝒄

This paper is devoted to the study of the running coupling constant $\alpha_s$ ($q^2$ ) of $\pi^-$ meson and protons from p+p and p+C interactions at 4.2 GeV/c. It is well known fact that the more correct value of the cut parameter $\Lambda_{QCD}$ in the formula of $\alpha_s$ ($q^2$ ) plays very important role in the obtaining the right values of the strong coupling constant $\alpha_s$ ($q^2$ ). The value of $\Lambda_{QCD}$, determined in previous works, was employed in our calculations,
\begin{equation}
\Lambda_{QCD}= (c \hbar) GeV = 0.197 GeV
\end{equation}

The values of $\alpha_s$ ($q^2$ ) obtained with this cut parameter are compared to the QCD predictions.

Speaker: Murdorj, Urangua (Mongolian Academy of Science, Institute of Physics and Technology)

Urangua Murdorj XXVI Baldin Seminar.pdf

14:00 → 15:40 Polarization phenomena, spin physics

Convener: Troshin, Valery (JINR)

14:00 EXCLUSIVE $J/\Psi$ PRODUCTION AND GLUON GPDs EFFECTS

Exclusive photoproduction of heavy $J/\Psi$ meson is performed within the handbag
approach where amplitudes factorize into hard subprocesses and generalized parton
distributions (GPDs). The general parton distributions (GPDs) for gluons $H_g$, are
constructed using double distribution representation. The calculated cross section for
few sets of $H_g$, GPDs describe fine $J/\Psi$ production experimental data from HERA to LHC energies \cite{1}.
Within this approach we estimate $J/\Psi$ spin asymmetries determined by $E_g$ and $H_g$ GPDs. Some
predictions for future electron-ion colliders in USA and China are done.

We extend our model calculations to exclusive $J/\Psi$ production in
proton–proton collisions. The survival factors and equivalent
photon approximation are applied to predict the exclusive
$J/\Psi$ production in pp collisions. Obtained results are in a good
agreement with the experimental data at LHCb \cite{2}. We predict the exclusive
$J/\Psi$ production cross section at RHIC and NICA energies.

Our GPD approach predictions can be employed to estimate the
exclusive $J/\Psi$ production abservables in future lepton–proton and proton–proton experiments
to get essential information on gluon GPDs.

1. S. V. Goloskokov, Ya-Ping Xie and Xurong Chen, Phys.Rev {\bfseries D110}, 076029 (2024),
   arXiv:2408.05800 [hep-ph].
2. Ya-Ping Xie, S. V. Goloskokov, Eur. Phys. J. C {\bfseries 85},680 (2025), arXiv:2502.17743 [hep-ph].

Speaker: Goloskokov, Sergey (JINR)

goloskokov_bld25.pdf

14:30 New developments in the ReneSANCe event generator

We give a report on new developments in the ReneSANCe Monte Carlo event generator. ReneSANCe is an event generator for simulation of the Standard Model processes at $ee$, $pp$ and $\gamma\gamma$ colliders.

Speaker: Sadykov, Renat (JINR)

sadykov_baldin_2025.pdf

14:50 On the equation of state of rotating gluon plasma

Using first-principle lattice simulations, we study the equation of state of rotating SU(3) gluodynamics. We expand the free energy of the rotating gluon system in a series of angular velocity and measure the first two non-zero coefficients of this expansion (the second and fourth order). The second-order coefficient is associated with the rigid moment of inertia of gluon plasma, while the fourth coefficient describes how rotation modifies the moment of inertia.

Speaker: Eremeev, Egor (JINR)

2025_16_09_baldin_conf-2.pdf

15:10 Relativistic quantum-mechanical description of acceleration of charged vortex particles by a uniform electric field

The relativistic quantum-mechanical description of a charged Laguerre-Gauss beam accelerated in a uniform electric field has been fulfilled [1]. Stationary wave eigenfunctions are rigorously derived. The evolution of the beam parameters during acceleration is considered in detail. The practically important effect of extraordinary suppression of transverse spreading of the beam is discovered, carefully analyzed, and properly explained. Our results provide direct evidence that vortex particle beams can be accelerated without destroying their intrinsic vortex properties, paving the way for high-energy vortex beam applications.
1. Qi Meng, Ziqiang Huang, Xuan Liu, Wei Ma, Zhen Yang, Liang Lu, A. J. Silenko, Pengming Zhang, and Liping Zou, Relativistic quantum mechanics of charged vortex particles accelerated in a uniform electric field, arXiv:2506.18492 [physics.acc-ph] (2025).

Speaker: Silenko, Alexander (Joint Institute for Nuclear Research)

BaldinAutumnSilenko.pdf

14:00 → 15:40 Progress in experimental studies in high energy centers - JINR, CERN, BNL, JLAB, GSI, etc.

Convener: Feofilov, Grigory (Saint-Petersburg State University)

14:00 Measuring distributions of quark and gluon jets by jet parameters at a hadron collider

Quark (q) and gluon (g) jets have significantly different parameters. The normalized distribution of jets by the jet parameter can be measured. This distribution is equal to the sum of the normalized distributions of g- and q-jets (q/g-templates) with weights aG and (1-aG), respectively, where aG is the g-jet fraction in jet sample. Therefore, to measure q/g-templates, it is necessary to measure aG in advance. After that, two q/g-templates can be measured. For this, two samples of jets with significantly different aG can be used. However, q/g-templates are not universal and depend on the jet selection channel. This non-universality has a kinematic nature and can be eliminated by selecting jets from two kinematically identical channels. The disadvantage of this method is that the requirement of kinematic equivalence of jet samples reduces the jet statistics. It is possible not to reduce the statistics and introduce corrections for the non-universality of q/g-templates using modeling. In this talk, a new method for measuring q/g-templates is proposed, which uses a single jet sample and measured aG in it. The missing information is extracted from a kinematically identical model sample using a q/g-discriminator. The fact that a single channel is used in the measurement is an important practical advantage of the proposed method.

Speaker: Dr Shulga, Sergey (JINR)

SShulga-Baldin-16Sept2025.pdf

14:30 The Liquid Scintillator Track Detector

A track detector based on a liquid scintillator is being developed at JINR VBLHEP. Liquid xenon is supposed to be used as the active medium in the final version of the detector. The detector is a steel vessel with windows for registration scintillation flashes. Light registration is carried out by position-sensitive elements - SiPM matrices of 8x8 cells. The purpose of the detector being developed is to register recoil nuclei from neutral particles, as in experiments searching for direct signals from dark matter. The results of the development of a detector using a LAB scintillator and testing of the detector by cosmic rays are presented.

Speaker: Ustinov, Valentin (JINR VBLHEP)

Ustinov_VV_Baldin_ISHEPP_XXVI_v2.pdf

15:00 Modern silicon and scintillation detector systems for the experiments at the NICA collider

In modern high-energy and elementary particle physics experiments, the proportion of silicon detector systems is growing. The world's leading experiments: ALICE, ATLAS, CMS at the Large Hadron Collider, STAR at the Relativistic Heavy Ion Collider (RHIC), MPD, SPD at the NICA collider currently use or plan to implement silicon pixel detectors as the basis of their tracking systems. These detectors improve the spatial resolution for reconstructing primary and secondary vertices of short-lived particles and enhance identification efficiency at low transverse momenta. Such capabilities are essential for studies in heavy-flavor physics, charmonium production, the space-time evolution of quark-gluon plasma, and exotic nuclear states. On the other hand, high-energy physics accelerators play an important role in applied research, including radiation materials science and life sciences. In these fields, new fast and radiation-hardness scintillators operating together with silicon photomultipliers (SiPMs) can be used.
The report presents an overview of modern detector technologies utilizing silicon pixel detectors and their applications in experiments at the NICA collider: MPD, SPD, ARIADNA. The results of experimental studies of silicon pixel detector properties will also be presented both in the context of fundamental experiments on the study of superdense nuclear matter in experiments at NICA, and in applied work developing new tomographic devices for hadron therapy. New developments will also be presented for the creation of a relativistic heavy ion beams intensity and composition monitoring system, designed for long-term irradiation facilities.
The reported study was supported by the Russian Science Foundation, project no. № 23-12-00042, https://rscf.ru/en/project/23-12-00042/

Speaker: Dr Zherebchevsky, Vladimir (Saint-Petersburg State University)

Presentation_Zherebchevsky_Main.pdf

15:40 → 16:00 Coffee break

16:00 → 18:00 Polarization phenomena, spin physics

Convener: Goloskokov, Sergey (JINR)

16:00 Lattice study of total momentum and free energy of rotating gluon plasma

In this report we present the results of our study of rotating gluodynamics. In particular, we carry out lattice calculation of total angular momentum of rotating gluodynamics for various temperatures and angular velocities within local thermalization approximation. In this approximation, instead of simulating the full action, we use the action with the coefficients being fixed at some distance from the axis of rotation. The results for the total gluon momentum are used to construct the free energy of rotating gluon plasma.

Speaker: Sychev, Dmitrii (BLTP JINR, MIPT)

Sychev_presentation_2025sep16_v2_8.pdf

16:20 Neutrino spin oscillations in the vicinity of a black hole.

We study spin oscillations of neutrinos which travel at an arbitrary angle with respect to the equatorial plane of a rotating black hole. The black hole is surrounded by a thick magnetized accretion disk. The gravitationally scattered neutrinos experience spin precession caused by the interactions of the neutrino magnetic moment with the toroidal magnetic fields in the disk as well as with the background matter. We present the results from our numerical studies.

Speaker: Deka, Mridupawan (JINR)

Deka.Mridupawan_Baldin_2025.pdf

16:50 Quantum field theory description of neutrino spin-flavor oscillations

We study spin-flavor oscillations of neutrinos in a magnetic field within the quantum field theory approach in which neutrinos are virtual particles. Neutrinos are taken to be Majorana particles having a nonzero transition magnetic moment. We derive the dressed propagators of the neutrino mass eigenstates exactly accounting for the magnetic field contribution. The matrix element and the transition probability for spin-flavor oscillations are obtained. The leading term in the transition probability is shown to coincide with the result of the standard quantum mechanical description of neutrino oscillations. We also derive the correction to the transition probability which has the quantum field theory origin.

Speaker: Dvornikov, Maxim (IZMIRAN)

17:10 Global polarization of lambda hyperon in the MPD experiment at NICA energies

The spin polarization of lambda hyperons exhibits an anisotropic alignment with the total orbital angular momentum of the collision system, serving as a probe for vorticity in the strongly-interacting matter. We study the lambda hyperon decay into a proton and a pion to measure global polarization in heavy-ion collisions, adopting an approach previously used by the STAR Collaboration to investigate the vortical structure of the produced medium. This method is now applied to Xe+Xe collisions at a center-of-mass energy of 2.87 GeV per nucleon pair, generated with the UrQMD model. The results provide a baseline for future experimental measurements with the MPD detector.

Speaker: Flusova, Daria (Joint Institute for Nuclear Research (JINR))

FlusovaDS.pdf

17:30 ESSENCE OF CHARGE AND SPIN WITH GENERAL COVARIANT DIRAC EQUATIONS

In the framework of field or quantum theory of the electromagnetism, presented by the Maxwell-Schrodinger and the Maxwell-Dirac equations, there is no an operator of the electric charge that could replace the artificial operation of charge conjugation and explain on the fundamental field-theoretical level a reason of the existence in the Nature the positive and negative electricity.

Duality of the natural time, presented at Baldin ISHEPP XXV, and general covariant Dirac equations give solution of this problem, connecting essence of charge with the natural time. These equations provide as well a natural explanation of the so-called generations, confinement and quark-lepton symmetry, predicting exactly the number of families. With this we have a reliable basis for the explanation of all phenomena connected with the existence of nuclei and a prediction of new one.

Speakers: Pestov, Ivanhoe, Pestov, Ivanhoe (Bogoliubov Laboratory of Theorewtical Physics, JINR)

BEPESTOV.pdf

16:00 → 18:00 Relativistic heavy ion collisions

Convener: Dr Zherebchevsky, Vladimir (Saint-Petersburg State University)

16:00 Study of the Higgs boson using various machine learning algorithms

After the discovery of the Higgs boson in the LHC experiments, measurements of its properties began. The measured mass of the Higgs boson is 125 GeV. At this mass, the probability of its decay into bb is about 58%, which means that more than half of the produced Higgs bosons decay into a pair of bb quarks. Therefore, this channel is very important for studying the properties of the Higgs boson. The most suitable production channel of the Higgs boson for decay to bb is the associated production with a vector boson. It was in this production channel that the decay of the Higgs boson into a pair of b quarks was first observed at the LHC in 2018. The Higgs boson is easier to study in the ZH associated production channel, where Z decays into a pair of charged leptons (electrons or muons), since the final state particles can be fully reconstructed in the detector. During the Run-1 of the LHC, physics analysis was carried out mainly using cut-based methods. At the start of the Run-2, the physical analysis began to be carried out using Multivariate Analysis (MVA) or Machine Learning (ML) methods. The ML method includes a large number of algorithms, and three of them, which are widely used in high energy physics, were used in this work: boosted decision tree (BDT), multilayer perceptron artificial neural network (TMlpANN), and deep neural network (DNN). The performance of these algorithms was compared. The input variables are the same as those used in the analysis in the ATLAS experiment and are the same for all three ML algorithms. About 3 million signal and 11 million background events were used for training. TMlpANN with optimal hyper-parameters outperforms the other two algorithms when using Root's Toolkit for MVA (TMVA). However, moving to more advanced frameworks such as TensorFlow or PyTorch changes the situation in favor of DNN. But in all cases, BDT remains the most efficient algorithm due to its high training speed.

Speaker: Ahmadov, Faig (JINR & IP MSE)

Higgs_ISHEPP_FAhmadov.pdf

16:20 Latest results of searches for invisible Higgs Boson decays in the ATLAS experiment

This report presents an overview of the latest results and research methodology of the search for Higgs boson decay into Dark Matter (DM) particles, using data obtained at first (√𝑠 = 7 TeV, 8 TeV ) and second (√𝑠 = 13 TeV ) Large Hadron Collider (LCH) Runs, corresponding to a luminosity of 4.9 - 19.7 and 139 - 140 fnb-1, respectively. Results were interpreted in the context of models where the Higgs boson acts as a portal to dark matter, where limits are set on the scattering cross section of weakly interacting massive particles and nucleons. Assuming the Standard Model cross section for the Higgs boson, an upper limit was set on the branching fraction into DM particles at 95% confidence level, obtained result is the most strict for ATLAS and CMS LHC experiments at the moment.
Further plans for the ATLAS experiment to study this process in Higgs Boson vector boson fusion production using partial Run 3 data are also presented.

Speaker: Pokidova, Marina (NRC Kurchatov Institute PNPI (RU), SPbPU)

baldin_conf.pdf

16:40 Two particles correlations in HIC

Speaker: Rogachevsky, Oleg

17:00 High-order net-proton cumulants and the event volume definition in A+A collisions at NICA energies.

High-order net-proton cumulants and the event volume definition in A+A collisions at NICA energies.

G. Feofilov, St. Petersburg State University, St. Petersburg, RF
E-mail: g.feofilov@spbu.ru

Thermodynamic predictions [1] have indicated that the non-Gaussian fluctuations of  the event-by-event observables, such as the net electric charge, the net strangeness  and the net baryon number, could be a very sensitive signal of the proximity of the critical point  (CP) of strongly interactive matter. This CP is being extensively searched at present in high-energy nucleus-nucleus collisions at the SPS at CERN and in BES-I and -II programs at RHIC. In particular, the higher-order cumulants of net-protons are being used as a proxy for net baryon number. Relevant studies are also in preparation  with the MPD experiment at NICA at JINR. 
However, the non-dynamical, trivial volume fluctuations of protons and net-protons could dominate  over the genuine physical signals of interest [2,3]. This is due to the fact that, in currently applied procedures, any selected class of collision centrality will contain the inevitable mixture of the events with different impact parameters (see in [4]). Thus the relevant trivial volume fluctuations will dominate over the signal of interest.
    We propose in this report the procedure to use, in the analysis of A+A collisions at NICA, the event-vise definition of the interaction volume in order to mitigate the influence of trivial fluctuations on the values of high-order net-proton cumulants.  This could be done event-by-event using the ML technique, similar to [5], for the number of nucleons-participants (Npart)  in the given collision.  The  value of Npart  estimated for the event is more relevant then the mean impact paparemeter, and it is also of particular importance due to the well known effect of nucleon stopping at NICA energies   that leads to the  bias of the net-proton number.

Acknowlegments: The author acknowledges Saint-Petersburg State University for a research project 103821868.
1. M.A.Stepanov, Phys. Rev. Lett. 102, (2009) 032301.
2. V. Skokov, B. Friman and K. Redlich, “Volume fluctuations and higher order cumulants of the net baryon number”. arXiv:1205.4756v2.
3. P.Braun-Munzinger, A.Rustamov, J.Stachel, Nuclear Physics A960 (2017) 114–130.
4. T. A. Drozhzhova,V. N. Kovalenko,A. Yu. Seryakov,G. A. Feofilov, Physics of Atomic Nuclei, 2016, V 79, Issue 5, pp 737–748
5. K. Galaktionov, V. Rudnev and F. Valiev, Physics of Particles and Nuclei, 2023, Vol. 54, No. 3, pp. 446–448.

Speaker: Feofilov, Grigory (Saint-Petersburg State University)

17:20 Neutral pion elliptic flow in p+Au collisions at 200 GeV

While elliptic flow ($v_2$) is a well-established signature of the quark-gluon plasma (QGP) in heavy-ion collisions, its observation in small collision systems remains a topic of active investigation. The LHC experiments first demonstrated the existence of $v_2$ in most central high-multiplicity collisions of p+p/Pb, which was soon complemented by the observation of collective effects in d+Au collisions at RHIC. Measurements of $v_2$ values in p+Au collisions provide further insight into the origin of observed azimuthal anisotropy in small collision systems and allow to determine whether it originates from collective flow or non-flow correlations. Due to superior signal-background ratio neutral pions ($\pi^{0}$) can extend the study of $v_2$ into lower multiplicity and higher transverse momentum ($p_T$) ranges.

This talk will present recent measurements of π⁰ $v_2$ as a function of $p_T$ in various centrality classes in p+Au collisions at 200 GeV. Obtained $\pi^{0}$ $v_2$ values in 0-5% centrality class are consistent with previous $\pi^{\pm}$, $h^{\pm}$ $v_2$ results at RHIC up to $p_T$ ≈ 2.5 GeV/c. This agreement also persists across the 20–40% centrality, where the $\pi^{0}$ $v_2$ measurements align with $h^{\pm}$ data. The consistency of $\pi^{0}$ $v_2$ with $h^{\pm}$ $v_2$ in the 40–60% centrality up to $p_T$ ≈ 4 GeV/c probably indicates a contribution from non-flow effects at higher $p_T$.

The $\pi^{0}$ $v_2$ values measured in 0-5% centrality class, characterized by the highest particle multiplicity, have been scaled with the number of constituent quarks ($n_q$). It was found that normalization of the measured $\pi^{0}$ $v_2$ values leads to agreement between the $\pi^{0}$ $v_2$/$n_q$ values and those for $\pi^{\pm}$ and $p^{\pm}$ within the uncertainties.

The results of the work can be expanded for use in the MPD experiment of the NICA project. The authors acknowledge support from the Ministry of Science and Higher Education of the Russian Federation, state assignment for fundamental research (code FSEG-2025-0009).

Speaker: Ms Komarova, Snezhana (Peter the Great St. Petersburg Polytechnic University)

Baldin_seminar_Komarova.pdf

17:40 Simulation of Heavy-Ion Collisions for the SPD BBC Phase 0 Detector

The study of heavy-ion collisions with intermediate energies is a key direction of the future experimental program at the NICA accelerator complex. Within the scope of the collider commissioning activities, the installation of Beam-Beam Counter (BBC) prototype (Phase 0) is planned at the SPD interaction point. To determine the preliminary operation conditions for the detector, the simulation of Xe+W collisions at 3 GeV/nucleon was performed using the Geant4 framework. Different event generators were used and compared to assess systematic uncertainties and enhance the reliability of the results. The simulation results are essential for optimizing the detector configuration and interpreting the first experimental data.

Speaker: Volkov, Ivan (LHEP-JINR, Dubna, Moscow region, Russia)

VolkovI_BBC_Phase0_HIC_Sim.pptx.pdf

Wednesday 17 September

09:00 → 19:00 Excursions

Thursday 18 September

09:00 → 10:40 Cumulative and subthreshold processes

Convener: Larionov, Alexei (Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, 141980 Dubna, Russia)

09:00 Cumulative processes and fractal structure of nuclei

author: Mikhail Tokarev
co-author: Imrich Zborovsky

Mikhail Tokarev$^{1 \natural}$ and Imrich Zborovsky$^{2 \flat}$

$^1$Joint Institute for Nuclear Research, Dubna, Russian
$^2$The Czech Academy of Science, Nuclear Physics Institute, Rez, Czech Republic

$^{\natural}$ E-mail: tokarev@jinr.ru
$^{\flat}$ E-mail: imrichzborovsky@gmail.com

Selection of cumulative events is assumed to enrich data samples by a new type of collisions characterized by higher energy density and more compressed matter. We expect that this will allow finding clearer signatures of phase transition, location of a critical point and studying extreme conditions in heavy ion collisions. The concept of $z$-scaling based on the principles of self-similarity, locality and fractality reflecting general features of particle interactions is reviewed. The concept was used to describe of high-$p_T$ particle production in cumulative and non-cumulative regions. The self-similarity variable $z$ is a function of the momentum fractions $x_1$ and~$x_2$ of the colliding objects carried by interacting hadron constituents and depends on the fractions $y_a$ and $y_b$ of the scattered and recoil constituents carried by the inclusive particle and its recoil counterpart. The scaling function $\psi(z)$ is expressed via inclusive cross-section, multiplicity density and three model parameters. Structure of the colliding objects and fragmentation processes is characterized by the structural and fragmentation fractal dimensions $\delta$ and $\epsilon$, respectively. The produced medium is described by a "specific heat" $c$. The change in parameters of the theory (a specific heat and fractal dimensions) near the critical point is considered as a signature of new physics. The results of data analysis of cumulative production in p+A and A+A collisions in collider and fixed target mode are discussed.

Speaker: Tokarev, Mikhail (Joint Institute for Nuclear Research)

ISHEPP25_Tokarev_23.pdf

09:30 Manifestation of nuclear effects in fractal analysis of Monte Carlo AMPT events using SePaC method

Manifestation of nuclear effects in fractal analysis of Monte Carlo AMPT events using SePaC method

T.G. Dedovich$^{1,2}$ and M.V. Tokarev$^{1,2}$
$^1$Joint Institute for Nuclear Research, Dubna, Russia
$^2$Dubna State University, Dubna, Russia
E-mail: tdedovich@jinr.ru

Search for extreme directions associated with changes in the state of matter is one of the tasks of modern high-energy physics. It is known that systems exhibit fractal behavior near phase transitions. Fractality (intermittency) of identified charged hadrons in the range of pseudorapidities |η|< 0.5 and transverse momentum 0.2 < pT < 2.0 GeV/c is studied in the STAR experiment at RHIC in AuAu interactions at energies √sNN = 7.7–200 GeV [1]. In the present work, the manifestations of nuclear effects on the results of fractal analysis of Monte Carlo (MC) AuAu events are studied. Events at the AuAu energy of √sNN = 200 GeV were obtained using A Multi-Phase Transport (AMPT) generator [2, 3]. Events of several centrality classes 0-5%, 5-10%, 10-20% and 30-40% were considered. Event-by-event fractal analysis carried out using the SePaC [4-7] method allows us to divide events into fractal and non-fractal ones. It was found that the selected fractal events have a complex pt-spectrum, and the spectrum of non-fractal events is approximated by an exponential in the region of average pt values. Nuclear effects such as final state interactions (FSI), nuclear shadowing, production of high transverse momentum minijets and quark-antiquark pairs are discussed in terms of their manifestation in the event-by-event fractal analysis. It is shown that final state interactions significantly increases the proportion of non-fractal events with exponential pt-spectrum. The absence of FSI and nuclear shadowing leads to dependence of the pt-spectrum slope on centrality. Production of high transverse momentum minijets and quark-antiquark pairs affects the shape of pt-spectra of fractal events.

1. M.I. Abdulhamid et al., Physics Letters B 845 (2023) 138165
2. Z.W. Lin, C.M. Ko, Phys. Rev. C 65, 034904 (2002).
3. Z.W. Lin et al., Phys. Rev. C 72, 064901 (2005).
4. T.G. Dedovich, M.V. Tokarev, Phys. Part. Nucl. Lett. 9, 552 (2012).
5. T.G. Dedovich, M.V. Tokarev, Phys. Part. Nucl. Lett. 10, 481 (2013).
6. T.G. Dedovich, M.V. Tokarev, Phys. Part. Nucl. Lett. 10, 491 (2013).
7. T.G. Dedovich, M.V. Tokarev, Phys. Part. Nucl. Lett. 18, 93 (2021).

Speaker: Dedovich, Tatiana (JINR)

Dedovich_Conf.pdf

09:50 MC modelling of high transverse momentum particle production in pp and dd collisions at NICA energies

Using event generators, simulations were performed of the production of particles with large transverse momenta in the central region of energies at the NICA collider. A large set of statistics was required to study the behavior of the inclusive cross section of rare processes, which include the production of particles near the kinematic boundaries of pp and dd reactions. In this region, the production of protons, pions, and kaons was investigated. The dependence of the inclusive cross sections for the production of these particles on transverse momentum and rapidity was found for several initial energies of the NICA collider. The dependencies found by MC simulation were compared with the predictions derived from the quark counting rules for inclusive cross sections in this area, which were obtained in works [1-4].

This work was supported by the Russian Science Foundation (grant 23-12-00042).

1. S. Yurchenko, V. Vechernin, Phys. Atom. Nucl. 88, 349 (2025)
2. V. Vechernin, S. Yurchenko, Int. J. Mod. Phys. E 33, 2441022 (2024)
3. V. V. Vechernin, S. V. Yurchenko, Moscow Univ. Phys. 79 (Suppl 1), 174 (2024)
4. V. V. Vechernin, S. N. Belokurova, S. V. Yurchenko, Phys. Part. Nucl. 55, 889 (2024)

Speaker: Yurchenko, Semyon (Saint Petersburg State University, Laboratory of ultra-high energy physics)

Yurchenko_ISHEPP_25.pdf

Yurchenko_ISHEPP_25.pptx

10:10 Formation of protons in a new cumulative region of central rapidities and large transverse momenta due to coherent coalescence of quarks

The production of protons with a large transverse momentum in the central rapidity region at high energies due to the process of coherent coalescence (recombination) of quarks is considered. The inclusive cross section of proton production is studied near the kinematic boundary of pp and dd reactions. In this kinematic region, explicit asymptotic formulas are obtained for the inclusive cross section based on the analysis of Feynman diagrams describing the production of protons due to the process of coherent recombination of quarks.
In particular, an asymptotic form of the dependence of the inclusive cross section on the distance to the kinematic boundary of the process for a given angle of emission (pseudorapidity) of the produced proton is found. The obtained expressions also allow tracing the dependence of the cross section on other dimensional parameters of the model - the geometric dimensions of the scattering objects and the mass of the constituent quark. A comparison of the obtained results with the quark counting rules for the inclusive cross-section of pion production in these processes, obtained earlier in the mechanism of fragmentation of a single quark into a pion [1,2], was carried out.
The developed approach and the obtained asymptotic dependences (new quark counting rules) for inclusive cross sections of proton and pion production can be verified experimentally by studying proton and pion production in the region of large transverse momenta and central rapidities in the SPD and MPD experiments at the NICA collider. We also note that for reliable registration of very rare particle production near the kinematic boundaries of pp and dd reactions and separation of their tracks from various kinds of false background tracks, it is highly desirable to have a signal from the Internal Tracking System, allowing confirmation of the exit of the track of the registered particle from the primary interaction vertex.
The authors are grateful to Saint-Petersburg State University for research project 103821868 and travel grant 137734523.

1. V. Vechernin, S. Yurchenko, Int. J. Mod. Phys. E 33, 2441022 (2024)
2. S. Yurchenko, V. Vechernin, Phys. Atom. Nucl. 88, 349 (2025)

Speaker: Vechernin, Vladimir (St. Petersburg State University)

Vechernin-Baldin-2025.pdf

09:00 → 10:40 Hadron spectroscopy, multiquarks

Convener: Абраамян, Хачик (JINR, Dubna)

09:00 Isospin symmetry violation in the strong decays of the spin-2 exotic state $X_2(4014)$

The isospin violation in the strong decays of the spin-2 exotic charmonium-like state $X_2(4014)$ into channels $\omega J/\Psi$ and $\rho^0 J/\Psi$ has been studied within the framework of the covariant confined quark model, designed to eliminate any UV divergences in quark loops. We have interpreted the exotic hadron $X_2$ as a four-quark state with a $D^*\bar{D}^*$ molecular-type interpolating quark current and computed the leading-order strong decay widths at the level of two-petal quark-loop diagrams. The partial widths of the above-mentioned decay modes and their branching ratio recently discussed in literature have been calculated and analyzed [1]. In the comparison of our approach to the recent $D^{*} \, \bar{D}^{*}$ molecular scenarios, we have shown the explicit appearance of the threshold effect in the latter models. The estimated branching ratio and calculated partial strong decay widths are in reasonable agreement with the latest experimental data. Our theoretical results might be checked by future experiments.

[1]. Gurjav Ganbold and M. A. Ivanov,
"Hidden-charm strong decays of the spin-2 partner of $X(3872)$",
Phys. Rev. D 111, 014007 (2025).

Speaker: Gurjav, Ganbold (Joint Institute for Nuclear Researches (JINR))

GurjavGanbold_BaldinXXVI_talk.pdf

09:30 NON-NUCLEONIC DEGREES OF FREEDOM IN TERMS OF THE QUARK CLUSTER APPROACH

Nuclear states, beginning with the six-quark Fock component of the deuteron, cannot be described solely in terms of conventional nucleon, meson, and isobar degrees of freedom in view of the presence of hidden-color states in any color-singlet multi-quark system. The momentum distribution of quarks in a nucleus is not a simple superposition of their distributions within nucleons. The EMC experiment at CERN was the first to establish this fact and many efforts were further made or planned (e.g. the NICA and EIC projects) to study the properties of quarks and gluons in the nuclear environment. In this work we develop the theoretical framework for study of hidden-color components of nuclei (including the nucleon-nucleon scattering states) on a basis of the QCD-motivated interaction [1] using methods of the nuclear cluster physics. We, citing the deuteron, show that a realistic description of the hidden-color component of the nucleus can be realized on a basis of the quark cluster model with taking into account 3 basic things: duality (a complementarity between the hadron and quark bases in studies of hadron data), the Pauli exclusion principle, and the requirement of the observed states be colorless. As a consequence it allows to evaluate weights of hidden color components of the deuteron including a possible dibaryon-like component of the NN wave function at the region of short distances [2]. These make possible to assess the behaviour of the deuteron form factors at large momentum transfer [3] and might be further used for interpretation of the A(e,e′NN), A(e, e′N∆) and A(e, e′∆∆) data dependent on the short-range NN correlations.

Speaker: Dr Obukhovsky, Igor (Institute of Nuclear Physics, Moscow State University)

obukhovsky.pdf

obukhovsky.ppt

09:50 Charge asymmetry in the process e+e− → π+π−π0ɣ

The charge asymmetry in the process $e^+e^-\to\pi^+\pi^-\pi^0\gamma$ is studied taking into account a longitudinal polarization of electrons (positrons) for photons with energies $\omega_\gamma\ll\sqrt{s}$. The asymmetry arises due to interference of amplitudes corresponding to production of pions in states with charge parity odd and charge parity even. One of the contributions to the charge asymmetry is given by the $a_1(1260)$ meson in the intermediate state. Unlike process $e^+e^-\to\pi^+\pi^-\pi^0$, the asymmetry is nonzero even without taking $a_1(1260)$ meson into account. However, taking $a_1(1260)$ meson into account significantly changes the shape of the asymmetry curve. It is shown that the charge asymmetry can reach several tens of percent.

Speaker: Obraztsov, Ivan (Budker Institute of Nuclear Physics)

ISHEPP XXVI_2025_Obraztsov.pdf

10:10 Search for dibaryon resonances in the reactions dd → dd$\pi\pi$ and pd → pd$\pi\pi$

The resonance peak observed by WASA@COSY in the total cross section of the reaction of two-pion production in the isoscalar channel of the reaction $pn\to d\pi^0\pi^0$ [1] at invariant mass 2380 MeV with the width of 70 MeV, is considered as one of the most realistic candidate to the dibaryon resonance [2]. The isospin of this resonance is I=0 and spin-parity $J^P=3^+$. A similar resonance structure was observed by ANKE@COSY in the differential cross section of the two-pion production reaction $pd\to pd\pi\pi$ at beam energies 0.8-2.0 GeV with high transferred momentum to the deuteron at small scattering angles of the final proton and deuteron [3]. In this case the kinematic conditions differ considerably from that in Ref. [1] and two final pions were not detected and, therefore, the isoscalar channel was not separated. Nevertheless, in the distribution over the invariant mass $M_{dππ}$ of the final $d\pi\pi$ system of the reaction $pd \to pd\pi\pi$ the resonance peak was also observed at $M_{dππ} ≈ 2.38$ GeV [3]. In order to explain these data, the two-resonance model [5] of the reactionpn → $d\pi^0\pi^0$ was applied in Refs. [4] by inclusion of the t-channel σ-meson exchange between the proton and deuteron in the reaction $pd\to pd\pi\pi$. Recently in Ref. [6] the reaction $\gamma d\to d\pi^0\pi^0$ was studied and an indication to excitation of isoscalar dibaryon resonance $D_{03}(2380)$ and more heavier dibaryons d(2470) and d(2630) was found. These resonances can be excited also in the reaction dd→ dd* at SPD NICA collider. In this work we estimated the differential cross sections of the reactions $pd\to pd\pi\pi$ and $dd \to dd\pi\pi$ assuming excitaion of the $D_{03}(2380)$ dibaryon by σ- meson exchange in t-channel as in Refs. [4] and calculated distributions over the invariant mass of the final $d\pi\pi$ system for these reactions. The extended model [7] for decay channels of the $D_{03}(2380)$ was used in this calculations.

[1] P. Adlarson et al. (WASA@COSY Collab.), Phys. Rev. Lett. 106, 242302 (2011).
[2] H. Clement, Prog. Part. Nucl. Phys. 93 (2017) 195.
[3] V. I. Komarov et al. (ANKE@COSY Collab.), Eur. Phys. J. A (2018) 54: 206.
[4] Yu. Uzikov, N. Tursunbayev, EPJ Web of Conf. 204, 08010 (2019);
N. Tursunbayev, Yu. Uzikov, SciPost Phys. Proc. 3 (2020) 056.
[5] M.N. Platonova, V.I. Kukulin, Phys. Rev. C 87, 025202 (2013).
[6] T.C. Jude et al., Phys. Lett. B 832 (2022) 137277.
[7] M.N. Platonova, V.I. Kukulin, Phys. Rev. D 103 (2021) 11, 114025.

Speaker: Uzikov, Yury (Joint Institute for Nuclear Researches)

Uzikov-talk-dibaryons-Baldin-2025.pdf

09:00 → 10:40 Projects NICA/MPD/SPD/BM@N at JINR

Convener: Parfenov, Peter (JINR, NRNU MEPhI)

09:00 DCS for TPC MPD: Integrating DIM and MasterScada 4D

The Detector Control System (DCS) of the Time Projection Chamber (TPC) in the NICA/MPD experiment uses DIM (Distributed Information Management System) for fast and reliable data transfer between TPC and MPD DCS. To provide a monitoring, we integrated DIM with the industrial SCADA system - MasterScada 4D. This solution can be applied to other MPD subdetectors.

Speaker: Sokolova, Sofiya

Sokolova.pdf

09:20 TPC geomeries for NICA MPD simulations

Modern experiments in physics are impossible without computer
simulations. The NICA MPD experiment also includes this stage.
The key element for accurate simulation is a detailed detector geometry. Geometry for physical modeling must contain information not only about the physical dimensions and materials of individual elements, but also information about the volumes formed in the detector. In addition special geometries that describes some features of the detector could be used. This talk is review about MpdRoot implementation of MPD TPC geometries for root/GEANT and ACTS software.

Speaker: Bychkov, Alexander (LHEP)

Bychkov_Baldin_seminar_2025.pdf

09:40 Study of the Response of the Forward Hadron Calorimeter and Forward Quartz Cherenkov Hodoscope in Xe+CsI Reactions at 3.8 AGeV at the BM@N

An experimental study of xenon–cesium iodide interactions at a kinetic energy of 3.8 AGeV was conducted during the first physics run of the BM@N experiment. The BM@N setup incorporates forward detectors: the Forward Hadron Calorimeter (FHCal) and the Forward Quartz Cherenkov Hodoscope (FQH), which are employed to determine the geometry of nuclear collisions. This work presents a comparison of the experimentally measured responses of the FHCal and FQH with the corresponding simulated responses obtained using the DCM–QGSM–SMM event generator.

Speaker: Karpushkin, Nikolay (INR RAS)

slides.pdf

10:00 Comparison of methods for determining centrality in nucleus-nucleus collisions in the BM@N experiment

Centrality determination is essential in relativistic heavy-ion collisions, as it establishes a quantitative relationship between the final-state observables and the collision impact parameter - the key variable governing the initial-state geometry and energy density. This mapping enables robust comparisons among experimental measurements, theoretical calculations, and results from different collision systems. Standard centrality estimators include charged-particle multiplicity, detector hit distributions, and forward energy deposition. The use of multiple independent estimators reduces autocorrelation biases and systematic uncertainties in the reconstructed collision geometry.
We present a novel centrality determination method based on Bayesian inference incorporating two simultaneous observables, which provides improved constraints on initial-state fluctuations. A systematic comparison is made between centrality frameworks using the Monte Carlo Glauber model and our Bayesian approach, applied to Xe+CsI collisions at 3.8A GeV recorded by the BM@N experiment. This analysis yields critical insights into model dependencies and the robustness of centrality determination at intermediate energies.

Speaker: Idrisov, Dim

Baldin2025.pdf

10:20 Simulation Study of Dileptons at $\sqrt{s_{NN}}$ = 9.2 GeV Bi-Bi Collisions at NICA-MPD

The Multi-Purpose Detector (MPD) at the NICA facility is designed to study heavy-ion collisions at $\sqrt{s_{NN}} = 4$–$11$ GeV, aiming to explore the baryon-rich region of the QCD phase diagram to investigate the possible existence of a first-order phase transition and a critical end-point. Dilepton measurements, particularly the invariant mass spectrum of dielectrons, serve as a key electromagnetic probe sensitive to the initial temperature, chiral symmetry restoration, and lifetime of the hot dense medium.

We will present a feasibility study of dielectron production in $\sqrt{s_{NN}} = 9.2$ GeV Bi+Bi collisions using full MPD detector simulations with realistic event generators. Details will be provided on electron reconstruction using the Time Projection Chamber (TPC), Time-of-Flight (TOF) detector, and Electromagnetic Calorimeter (ECal), background suppression techniques for photon conversions and $\pi^0$ Dalitz decays and performance evaluation based on signal-to-background ratio (S/B) and statistical significance ($n_{\sigma}$). These established reconstruction and background suppression procedures provide support for future experimental data analysis, and the results verify the ability of MPD to perform high-precision dilepton measurements.

Speaker: Wang, Yonghong (JINR， Shandong University)

Yonghong_Baldin2025_V1.pdf

Yonghong_Baldin2025_V1.pptx

10:40 → 11:00 Coffee break

11:00 → 13:00 Cumulative and subthreshold processes

Convener: Tokarev, Mikhail (Joint Institute for Nuclear Research)

11:00 A model of cumulative proton production in the process $pd \to ppn$

Production of particles in reactions on nuclear targets in the kinematical region forbidden in the case of free proton target, i.e. cumulative region, is still a challenge to theoretical models. That is because the simplest impulse approximation fails to provide large enough cross sections for large momentum cumulative particles, even when Fermi motion is taken into account. This led to several possibilities ranging from the multiple rescattering and thermal mechanisms to the exotic scenarios of interaction with density fluctuations and multi-quark clusters. In this talk, the method of the generalized eikonal approximation based on the multiple scattering diagrams is discussed in the application to the backward proton production in exclusive $pd \to ppn$ reaction. The model includes one- and two-step rescattering diagrams with intermediate nucleon and $\Delta(1232)$ resonance. Thereby, the spin-isospin structure of the deuteron and the antisymmetry of the full reaction amplitude are carefully taken into account. Numerical implementation of the model is performed in the form of a Monte Carlo event generator. The model describes existing data on the spectra of backward protons at relativistic energies, including the JINR data for $dp$ collisions at 3.33 GeV/c [1] and $pd$ collisions at 8.6 GeV/c [2] quite well. Predictions for cumulative proton spectra in $pd \to ppn$ in the NICA SPD regime are provided.

[1] B. S. Aladashvili et al. (Warsaw-Dubna), Yad. Fiz. 27, 704 (1978).

[2] A. M. Baldin et al., “Cumulation of Light Nuclei,” (1977), JINR-P1-11168.

Speaker: Larionov, Alexei (Bogoliubov Laboratory of Theoretical Physics, Joint Institute for Nuclear Research, 141980 Dubna, Russia)

larionov_ISHEPP2025.pdf

11:20 Development of experimental research program for multi-quark systems at high pT on Nuclotron

The project is aimed at an experimental search and study of the properties of multi-quark (multi-nucleon) states on fixed target experiments with polarized and unpolarized beams of light nuclei of Nuclotron. The unique energy range of the Nuclotron and the high intensity of ions, including polarized ones, combined with the use of cryogenic and polarized targets opens up the possibility of conducting exclusive and correlation studies of rare processes in NN-, dd-, NA- and AA interactions when particles are produced in the range of pT > 0.5 GeV/s. The report discusses proposals for studying the properties of diquarks, their flavor composition, as well as the formation of 6-quark states in pp, pn exclusive reactions. Proposals for the experimental search and study of the properties of cold dense baryonic matter and for studies of the formation of strange baryons at high baryon densities are also being discussed.

Speaker: Sharkov, Georgy (МИФИ)

2025 Baldin Seminar Sharkov Shimansky Stavinsky High pT at Nuclotron.pdf

11:50 Time-of-flight and coordinate criteria for two neutros identification with 3D neutron detector

Algorithm for identification two neutrons in a 3D neutron detector is discussed. Time of flight and spatial criteria for separating one- and two-neutron events are proposed. The efficiency of the proposed criteria is estimated.

Speaker: Stavinskiy, Alexey (NRC "Kurchatov Institut" -ITEP/JINR)

12:10 Topological identification criteria two-neutron events in 3d neutron detector

The procedure for separating one- and two-neutron events by the number of active cells, the number and shape of clusters is presented. This procedure is effective even in the case of identical neutron energies, when criteria based on time-of-flight information are not applicable. The results of Monte Carlo simulation with the Geant4 toolkit of the interaction of single and double neutrons with energies from 0.5 to 4 GeV in the 16-layer neutron detector are presented.

Speaker: Sakulin, Dmitriy (JINR)

Sakulin.pdf

11:00 → 13:00 Hadron spectroscopy, multiquarks

Convener: Гуржав, Ганболд (Joint Institute for Nuclear Researches (JINR))

11:00 Charmonium and bottomonium electromagnetic characteristics in relativistic quark model

Speaker: Dr Haurysh, Vadzim (Sukhoi State Technical University of Gomel)

HauryshAndreev_Baldin2025.pdf

11:20 Heavy tetraquarks in the hyperspherical approach

Within the framework of the quark model and the hyperspherical coordinate method, we study the bound states of four heavy quarks (tetraquarks). In the hypercentral approximation, the Schrödinger equation is reduced to a one-dimensional equation after averaging over the hyperspherical angles. An analytical solution to this equation was obtained using the variational method, along with a numerical solution. The hyperfine structure of the spectrum was calculated. To improve the accuracy of the calculations, corrections to the energy levels from the Breit Hamiltonian were taken into account.

Speaker: Martynenko, Fedor (Samara University)

martynenko_fa_ICHEPP2025.pdf

11:40 Searches for glueballs at BESIII

The search for glueballs – colorless bound states of gluons – is one of the most important tasks within the modern QCD. While parameters of glueballs are predicted under a wide range of models, their experimental observation is extremely difficult due to the mixing with the conventional mesons. Glueballs are predicted to be abundantly produced in glue-rich processes, such as charmonia decays. In this talk we present results of searches for various glueball states performed using uniquely large datasets of charmonia decays obtained by the BESIII experiment.

Speaker: Mr Egorov, Prokhor (LNP JINR)

Search for glueballs at BESIII.pdf

12:00 Neutral and charged decay modes of the X17 boson observed in dCu collisions at a momentum of 3.8 GeV/c per nucleon

Neutral and charged decay modes of the X17 boson observed in dCu collisions at a momentum of 3.8 GeV/c per nucleon

Kh.U. Abraamyan$^{1,2 *}$, Ch. Austin$^{3}$, M.I.
Baznat$^{4}$,
K.K.~Gudima$^{4}$,
M.A. Kozhin$^{1}$,
S.G. Reznikov$^{1}$, and A.S. Sorin$^{1,5}$

$^1$VBLHEP JINR, 141980 Dubna, Moscow region, Russia\
$^2$International Center for Advanced Studies, YSU, 0025, Yerevan, Armenia\
$^3$ 33 Collins Terrace, Maryport, Cumbria CA15 8DL, England\
$^4$ Institute of Applied Physics, MD-2028 Kishinev, Moldova\
$^5$ BLTP JINR, 141980 Dubna, Moscow region, Russia

*E-mail: abraamyan@jinr.ru

Earlier (see [1]-[3]) we reported the observation of structures at about 17 and 38 MeV/$c^2$ in the invariant mass spectra of photon pairs.
The results of testing of the observed signals, including the results of the
Monte Carlo simulation support the conclusion
that the observed signals are the consequence of detection of the particles with
masses of about 17 and 38 MeV/$c^2$ decaying into a pair of photons.

A comparative analysis of two series of measurements with two scintillation counters switched on in coincidence and without them, all other conditions being equal, are performed.
Thus, together with the decay mode of $X17$ into two photons, the charged mode ($e^{+}e^{-}$) of the decay of X17 is also confirmed. According to preliminary estimates, the partial widths of
these decays are comparable.

[1]. Kh.U. Abraamyan et al., "Observation of Structures at $\sim$17 and $\sim$38 MeV/$c^2$ in the $\gamma\gamma$ Invariant Mass Spectrum in dCu Collisions at a
Momentum of 3.8 GeV/c per Nucleon," Physics of Particles and Nuclei, 2024, Vol. 55, pp. 868-873.

[2]. Kh.U. Abraamyan, "Check of the structure in photon pairs spectra at the invariant mass of about 17 MeV/$c^2$," Acta Physica Polonica B Proceedings Supplement {\bf 17}, 6-A1 (2024).

[3]. Kh.U. Abraamyan et al., arXiv:2311.18632v1 [hep-ex].

Speaker: Dr Abraamyan, Khachik (JINR, Dubna)

Baldin_XXVI_2025_Abraamyan.pdf

Baldin_XXVI_2025_Abraamyan.pptx

11:00 → 13:00 Projects NICA/MPD/SPD/BM@N at JINR

Convener: Flusova, Daria (TPU)

11:00 A Monte Carlo simulation of the MPD experiment performance for strange particle decay study

Study of strange particle production in nuclear collisions is one
of the most important items of the physics program of the MPD experiment.
As previously demonstrated on simulated data, the detector will provide
good conditions for reconstruction of strange particles via their
weak decays to charged products in the collider mode of NICA operation.

In this work, it is shown that the detector will be capable of
successfully reconstructing strange particle decays also in the
fixed-target mode. This allows one to extend the experiment coverage
to lower energies comparable with the energy range of the BM@N experiment.

The simulated results on strange particle production study at the
MPD experiment in both the collider and fixed-target modes will be presented.

Speaker: Suvarieva, Dilyana (JINR)

Suvarieva_Dilyana_Baldin_2025_LHEP_1.pdf

11:20 Why is it interesting to study proton-deuteron collisions at √s ≈ 8.9 – 9.7 GeV and - t = 0.6 – 1.8 GeV2

Currently, there are serious contradictions in the description of p-d scattering at sufficiently high energies and momentum transfer. They manifest themselves not only between theory and experiment, but also between the results of two different experiments of high quality for their time. Thus, the differential cross sections of elastic p-d scattering at √s = 8.9 – 9.7 GeV and |t|= 0.6 – 1.8 GeV2, obtained at CERN [1] and FNAL [2], differ from each other by about two times. At the same time, the results of calculations of these cross sections performed within the framework of the Glauber model give values noticeably lower than the experimental ones for the both cases.
The difference between theory and experiment, in principle, can be explained using the idea of polymorphism of nuclear matter, which allows for the presence of hexaquark admixture in the deuteron [3]. For large momentum transfer, scattering on hexaquarks occupying a small spatial volume can give a significant contribution to the cross-sections. If the hexaquark, after being knocked out of the nucleus, turns into a deuteron, then it becomes clear why the Glauber model, which describes scattering on the nucleus in terms of scattering on its nucleons, does not explain the experimentally observed elastic scattering cross sections.
In addition, the hexaquark, after being knocked out of the nucleus, can with some probability transform into the excited state of the deuteron – dibaryon d. Some features of registration of dibaryons in colliding beams of protons and deuterons at the NICA SPD will be discussed too in this report. The relevance of setting up such an experiment at present is inspired by registrations of some new light dibaryons, which have been announced in [4, 5]. If such light dibaryons do exist, then for inelastic p + d --> p + d events scattered proton momentum losses fell in the kinematic region close to those for the elastic processes. Due to errors in measurement of scattered protons momenta, such events might be classified as elastic ones in [1]. Perhaps this explains the difference in the differential cross sections of elastic scattering obtained in [1] and [2].
References
1. U. Amaldi et al., Nucl. Phys. B39 (1972) 39
2. J. Engler et al., Nucl. Phys. B62 (1973) 160
3. V. A. Matveev, P. Sorba, Lett. Nuovo Cim., 20 (1977) 435
4. T. Ishikawa et al., Nucl. Phys. B789 (2019) 413
5. T. C. Jude et al., arXiv:2202.08594 [nucl-ex]

Speaker: Kostenko, Boris (JINR)

11:40 Method for increasing the efficiency of registration of minimum ionizing particles by fast detector on microchannel plates.

Method for increasing the efficiency of registration of minimum ionizing particles by fast detector on microchannel plates.
F.F.Valiev, N.I.Kalinichenko, A.Kozhedub, N.A.Makarov, V.N.Popov, G.A.Feofilov
St. Petersburg State University

Fast detectors on the microchannel plates (MCPs) have high time characteristics (short pulses of ~2 ns at the base, with a front at < 800 ps). They were proposed earlier [1] for registration of minimum ionizing particles (MIPs) formed in nucleus-nucleus collisions, the event-by-event determination of the start signal (T0), the primary vertex position and for the suppression of events of  collisions with residual gas in the beam pipe. In addition, it was shown in [2] with machine learning algorithms that the event-by-event analysis of the centrality of collisions of relativistic nuclei is also possible using time-of-flight information from the MCP detectors. It is especially important in the search for critical fluctuations in the MPD experiment at the NICA collider. MCP detectors have a large intrinsic gain, which in the case of a chevron assembly reaches values of ~106, 107. However, this advantage results in an increase in its own noise (the dark current of the MCP). Therefore,  the detection thresholds should be introduced leading, as a result, to some  decrease in the efficiency of detectors on the MCP (to ~ 80%) [3].
In this paper, we propose a method to increase the detection efficiency of MIPs while simultaneously reducing the background of the detecting device by several orders of magnitude. We show that by reducing the registration thresholds and introducing a nanosecond considence scheme for signals from two MCP detectors mounted in series on the MIP trajectory, it is possible to obtain an increase in the detection efficiency of minimally ionizing particles (~95%) with a simultaneous decrease in the background (less than ~10-3 1/(sec . cm2)). The possible application of this low-noise detector for recording cumulative particles in experiments at the NICA collider is discussed.

The authors acknowledge Saint-Petersburg State University for a research project 103821868

[1] A. A. Baldin, G. A. Feofilov, P. Har’yuzov, and F. F. Valiev,, “Fast beam-beam collisions monitor for experiments at NICA,” Nucl. Instr. Methods Phys. Res., Sect. A 958, 162154 (2020).
[2] K. Galaktionov, V. Rudnev , and F. Valiev , “Application of Neural Networks for Event-by-Event Evaluation of the Impact Parameter “, Physics of Particles and Nuclei, 2023, Vol. 54, No. 3, pp. 446–448.
[3] F.F.Valiev et al.“Microchannel plates as a detector for 800 MeV/c charged pions and protons “ JINR Rapid Communications. 1991. No 4/50/-91. p.27-36

Speaker: Mr Makarov, Nikodim (Saint-Petersburg State Universoty)

Nikodim Makarov-method-Baldin conf-2025-f.pdf

12:00 Cosmic-rays generators test using ECal/MPD experimental data

One of the important parts of the MPD experiment is the electromagnetic calorimeter ECal, which consists of 50 half-sectors, each containing 768 cells (towers) of different types and spatial orientations [1]. To test the calibration procedure on cosmic ray muons, the half-sector position was changed by rotating it around the central axis, which corresponded to its positions in the final calorimeter assembly. In this report, the effect of the half-sector rotation on calibration coefficients is presented for both experimental and simulation data. The experimental data can also serve as a good test of the angular distribution obtained within the framework of various cosmic ray generators [2, 3].

Bibliography

[1] M. A. Martemianov et al., Phys. Atom. Nucl. 88, № 1, 96 (2025).
[2] P. Shukla and S. Sankrith, Int. J. Mod. Phys. A 30, 1850175 (2018).
[3] D. Pagano et al., Nucl. Instrum. Meth. A 1014, 165732 (2021).

Speaker: Martemianov, M. A. (NRC “Kurchatov institute”, Moscow, Russia; NRNU MEPhI, Moscow, Russia)

Baldin2025-Martemianov.pdf

12:20 Directed flow of deuterons in Xe+Cs(I) collisions at 3.8A GeV at the BM@N experiment

Collective flow measurements in relativistic heavy-ion collisions can provide key constraints on the properties of strongly-interacting matter and its Equation of State (EoS) in the high net-baryon density regime. Light nuclei, such as deuterons, are particularly valuable in this context: their v1 coefficients are sensitive to the early-stage pressure gradients, and help distinguish between mechanisms of cluster formation. Accurate experimental data on deuteron directed flow can therefore serve to test and refine a broad range of theoretical approaches, including hydrodynamic, transport, and coalescence-based models. In this work, we report the first measurement of the directed flow of deuterons in Xe+Cs(I) collisions at a beam kinetic energy of 3.8A GeV, performed at the BM@N experiment and compare it to the world data.

Speaker: Zhavoronkova, Irina (National Research Nuclear University MEPhI)

Zhavoronkova_BaldinSeminar.pdf

12:40 Microservices for online event data handling in MPD experiments

Speaker: Mr Krylov, Victor (Joint Institute for Nuclear Research (JINR))

13:00 → 14:00 Break

14:00 → 15:40 Relativistic heavy ion collisions

Convener: Bikmetov, Nikita (Tomsk Polytechnic University)

14:00 NONPERTURBATIVE KINETIC DESCRIPTION OF THE VACUUM QGP PRODUCTION IN THE ABELIAN PROJECTION METHODS

The initial variant of the nonperturbative kinetic theory (NPKT) in the vacuum quark-antiquark creation in the conditions of the ultrarelativistic heavy-ion collisions was represented in a simplified semiphenomenological form as the Abelian projection of QCD, where the U(1) gauge theory with the masses and color charges of the light quarks was used for primary investigation of some features of such kind process (Rev. [1]). In the following development of NPKT was shifted in the strong field SFQED (Rev. [2-4]) and the low energy graphen model [5].

In the present work we return to analysis of NPKT in the method of the Abelian projections of QCD and discuss some concrete realizations of such kind QCD models of the chromoelectric fields generated by counterpropagating valent quarks flows. A chromoelectric feature in the QGP behavior is presence of the superposition of the forced of Langmuir plasma oscillations, which are well known in the electron-positron plasma created from the vacuum [6,7]. We compare also the obtained results with results of the work based on some alternative approach (e.g., [8]).

The main difficulty on the way to construction NPKT in QCD is multicomponents character of the theory, in contrast to the SFQED and the graphene [5]. These obstacles are encountered on the stage of diagonalization of the Hamiltonian. In this work we investigate these problem in the framework of the SU(2) model of QCD in combination with method of the direct diagonalization of the Hamiltonian [5].

1. D. V. Vinnik, V. A. Mizerny, A. V. Prozorkevich, S. A. Smolyansky and V. D. Toneev, Phys. At. Nucl. 64, 775 (2001).
2. A. Fedotov, A. Ilderon, F. Karbstein, B. King, D. Seipt and H. Taya, Phys. Rep. 1010, 1 (2023).
3. I. A. Alexandrov, V. V. Dmitriev, D. G. Sevostyanov and S. A. Smolyansky, Eur. Phys. J. Spec. Top. 229, 3469 (2020).
4. H. Abramowicz et al., Letter of Intent for the LUXE Experiment, arXiv:1909.00860 [hep-ex].
5. S. P. Gavrilov, D. M. Gitman, V. V. Dmitriev, A. D. Panferov and S. A. Smolyansky, Universe 6, 205 (2020).
6. D. B. Blaschke, B. Kämpfer, S. M. Schmidt, A. D. Panferov, A. V. Prozorkevich and S. A. Smolyansky, Phys. Rev. D 88, 045017 (2013).
7. R. Z. Jiang, C. Gong, Z. L. Li and Y. J. Li, Phys. Rev. D 108, 076015 (2023).
8. M.-R. Jia, F. Wan, C. Lv and B.-S. Xie, Commun. Theor. Phys. 70, 430 (2018).

Speaker: Dmitriev, Vadim (Saratov State University)

Dmitriev-ISHEPP5.pptx

14:20 Holographic equation of state matched with hadron gas EoS as a tool for the study of the QGP evolution

At the beginning of the 21st century, a new phase state of strongly interacting matter was established, known as the quark-gluon plasma (QGP) [1]. To study the formation of the QGP in collisions of heavy nuclei, the solution of a system of equations of relativistic hydrodynamics with a specific equation of state (EoS) is typically employed. In light of difficulties for non-zero baryonic potentials within Lattice QCD, various holographic models based on the well-known AdS/CFT duality have been proposed to obtain EoS for the QGP using the thermodynamic properties of the corresponding black brane in AdS$_5$.

In the present work, a calibration method is proposed for the holographic EoS developed by I. Ya. Aref'eva's theoretical group [2] to study QGP properties within the framework of relativistic hydrodynamics. Machine learning methods were applied to address the regression and optimization issues during the calibration of the relevant parameters using the LQCD results for quark masses that approximate the physical values [3]. Special attention is paid to the matching of the equation of state with the hadron gas EoS for low temperatures, which is common for lattice instruments [4]. The advantage of holography in this context is the possibility of matching at almost any baryonic potentials. For practical applications in studying heavy-ion collisions, the corresponding holographic EoS was incorporated into the relativistic hydrodynamics packages MUSIC [5] and vHLLE [6].

To obtain the final hadron spectra, numerical simulations were conducted using the iEBE-MUSIC and SMASH-vHLLE frameworks, which additionally include a set of packages for initial conditions, freeze-out and hadronic afterburner. Consequently, the transverse mass distributions of produced hadrons were calculated at the energies of NA49 experiment. The effect of matching holographic EoS with the HRG equation on the above results is discussed.

The authors acknowledge Saint-Petersburg State University for a research project 103821868.

References
[1] J. Adams et al. (STAR Collab.), Nucl. Phys. A 757 102 (2005)
[2] I. Aref’eva, K. Rannu, P. Slepov, Holographic anisotropic model for light quarks with confinement-deconfinement phase transition, J. High Energ. Phys. 2021, 90 (2021).
[3] M. Cheng et al., QCD equation of state with almost physical quark masses, Phys. Rev. D 77, 014511 (2008)
[4] P. Huovinen, P. Petreczky, QCD Equation of State and Hadron Resonance Gas, Nucl. Phys. A, 837, 1-2 (2010), pp. 26-53
[5] B. Schenke, S. Jeon, C. Gale, (3+1)D hydrodynamic simulation of relativistic heavy-ion collisions, Phys. Rev. C 82, 014903 (2010)
[6] Iu. Karpenko, P. Huovinen, M. Bleicher, A 3+1 dimensional viscous hydrodynamic code for relativistic heavy ion collisions, Comput. Phys. Commun. 185 (2014), 3016

Speaker: Anufriev, Anton (Saint Petersburg State University)

Anufriev_Kovalnko_Baldin_2025.pdf

14:40 Exploring α-Particle Emission Induced by Relativistic Muons in Nuclear Emulsion

Nuclear fragmentation first observed in photographic emulsions exposed to cosmic rays and is now studied with greater precision using nuclear track emulsion (NTE) irradiated by relativistic muons. This approach offers a unique way to investigate multi-fragmentation processes induced purely by electromagnetic interactions [1]. Within the BECQUEREL experiment [2], we examined μ-nucleus interactions in NTE, focusing on short-range α-particle tracks arising from the 3α breakup of carbon nuclei in μ + ¹²C → 3α reactions. Alpha particle kinetic energies were reconstructed for each event by simulating their ionization energy losses in NTE with SRIM software, while full 4π-geometry track reconstruction allowed precise determination of emission angles. These measurements facilitated the extraction of combinatorial invariant mass spectra for 2 and 3 α systems, offering new insights into the dynamics of μ-induced nuclear fragmentation and the mechanisms of α-particle emission.

References
1. D. A. Artemenkov, V. Bradnova, et al., Phys. At. Nucl. 78, 579-585 (2015), doi:10.1134/S106377881504002X [arXiv:1407.4572].
2. P. I. Zarubin, Lect. Notes Phys. 875, 51-93 (2014), doi: 10.1007/978-3-319-01077-9_3 [arXiv:1309.4881].

Speaker: Dr NATARAJAN, MARIMUTHU (Joint Institute for Nuclear Research)

Baldin_Conference_Marimuthu_180925.pdf

15:00 Predictions in modified Glauber model of total charged-particle yields in 16O +16O and 20Ne+20Ne collisions at LHC

In this talk we present the results of application of the Monte Carlo
modified Glauber model [1], [2], [3] for the predictions of collision centrality dependence of the total charged-particle yields for 16O +16O and 20Ne+20Ne colliding systems at the LHC.
Our model differs from the Standard Glauber model by the effective account of the energy losses in successive inelastic nucleon-nucleon collisions. For this purpose, a single model parameter k is defined as a mean fraction of momentum loss in each inelastic binary nucleon collision. Therefore, the decrease of momentum after each inelastic collision is followed by the associated decrease of the inelastic cross section and of the mean multiplicty yield, both are taken into account in the MC model in the next inelastic binary interaction.

The value of k is obtained by fitting the available data on the total chtarged-particle multiplicity yields measured in high-energy nucleus-nucleus collisions. Thus a single-parameter model provides good decription [3] for the nonlinear effects in multiplicity yields as a function of number of participating nucleons (Npart) observed in Pb+Pb collisions at RHIC and the LHC. To predict the dependence of the total charged-particle yields for light (16O +16O and 20Ne+20Ne) colliding systems, we use the modified Glauber model with the same value of k as defined in Pb+Pb collisions at 2.76 and 5.02 TeV. Results show, that in both cases of 16O +16O and 20Ne+20Ne colliding systems, the multiplicty yields, normalised on pairs of Npart, will linearly grow with Npart. This behaviour is different from the one of the heavy ion collisions. It is qualitively similar only to the one obseved in very peripheral Pb+Pb collsiions.
We discuss the purely geometrical effects for these light colliding systems that could be considered useful in future studies of QGP properties in energy density scanning.

The authors acknowledge Saint-Petersburg State University for a research project 103821868

[1] Feofilov G. A., Ivanov A. A. // Journal of Physics G: Nuclear and Particle Physics. – 2005. – Vol. 31, No. 5. – P. 230-237.
[2] G. A. Feofilov and A. Yu. Seryakov, AIP Conf. Proc. 1701, 070001 (2016); DOI:10.1063/1.4938686
[3] S. Simak and G. A. Feofilov, Phys. Part. Nucl. 56, 877 (2025).

Speaker: Simak, Svetlana

Балдинская 2025.pdf

15:20 Centrality determination in heavy-ion collisions at the NICA energy range.

Centrality is a key parameter characterizing the geometry of relativistic heavy-ion collisions, defining the size of the interaction region and enabling comparisons with model predictions and other experimental results. The Glauber method, based on charged-particle multiplicity, is reliable at high energies but, at low energies with small multiplicities, exhibits uncertainties in impact parameter estimation. In this study, we investigate both the Glauber method and an alternative approach based on Bayes’ theorem for centrality determination in collisions at the NICA energy range. The procedures were performed employing charged-particle multiplicity distributions generated by state-of-the-art models of nucleus–nucleus collisions.

Speaker: Demanov, Alexander

Baldin2025_cent.pdf

14:00 → 15:40 Structure functions of hadrons and nuclei

Convener: Kotikov, Anatoly (JINR)

14:00 Electron structure functions

Properties and applications of QED parton distribution and fragmentation functions are discussed. Optimization of the factorization scale choice is demonstrated for specific processes. A new factorization scheme is proposed for Drell-Yan processes in QED. Features of QED and QCD parton distribution functions are compared.

Speaker: Arbuzov, Andrej (BLTP JINR)

arbuzov_Baldin_2025.pdf

14:20 Relativistic generalization of the Faddeev-Yakubovsky equation

The constant growth of energies in particle accelerators gives grounds to raise the question of studying few-nucleon atomic nuclei within the framework of the relativistic approach. The well-studied quantum mechanical formalisms of Faddeev [1] and Yakubovsky [2] are not suitable for this due to their non-relativistic nature.
In our recent work [3], we carried out a relativistic generalization of the non-relativistic FY equation [2] to the relativistic case using the method developed in [4,5] for the three-particle case. In this work, we also solved the resulting system of integral equations by the iteration method and calculated the binding energy and the amplitudes of the states of the helium-4 nucleus. But in doing so, we made a number of assumptions, namely, we omitted the terms corresponding to the “2+2” subchannel from the equation.
In the present work, the relativistic FY equation was considered in its full form, taking into account the “2+2” subchannel. Rank-one separable potentials were used as nucleon–nucleon interaction potentials. Only states with zero orbital angular momentum were considered. The integral equation was solved by the iteration method. The binding energy and amplitudes of the helium-4 nucleus states were found. Calculations showed that taking into account the “2+2” subchannel leads to a decrease in the binding energy by 2–7 MeV depending on the potential and the considered state of the nucleus. This change shifts the calculation result closer to the experimental data. The studies conducted in this paper show that calculations using the relativistic generalization of the FY equation give realistic results. This gives reason to believe that replacing the simplest components of the formalism with more advanced ones will yield results superior in accuracy to non-relativistic calculations, as was the case in the study of the triton and helion using the BSF formalism. Namely, it is planned to use more accurate multi-rank NN-interaction potentials first.

1.Л. Д. Фаддеев, ЖЭТФ т. 39, стр. 1459 (1960)
2.O. A. Jacubovsky, Sov. J. Nucl. Phys. V. 5,  P. 1312 (1967)
3.С. Г. Бондаренко, С.А. Юрьев, Ядерная Физика т. 87, № 6, стр. 822-828 (2024)
4.G. Rupp, J. A. Tjon, Phys. Rev. C V. 37, P. 1729 (1988)
5.G. Rupp, J. A. Tjon, Phys. Rev. C V. 45, P. 2133 (1992)

Speaker: Dr Yurev, Sergey (JOINT INSTITUTE FOR NUCLEAR RESEARCH)

ISHEPP_Yurev.pdf

14:40 T-odd and T-even hadronic structures of the Drell-Yan process. Small Q_T/Q expansion

We present detailed analysis of the T-even and T-odd lepton angular distribution in the Drell-Yan
process including γ/Zˆ0 gauge boson exchange and using perturbative QCD based on the collinear
factorization scheme at leading order in the α_s expansion and α_sˆ2 for T-odd . We focus on the
study of the transverse momentum Q_T dependence of the corresponding hadronic structure functions and angular coefficients up to next-to-next-to-leading order in the Q_Tˆ2/Qˆ2 expansion. We
analyze Q_T dependence numerically and compare T-even angular coefficients with available data
of the ATLAS Collaboration at LHC.

Speaker: Zhevlakov, Alexey (TSU)

Zhevlakov_Baldin_2025.pdf

15:00 Space-like pion off-shell form factors in the Bethe-Salpeter approach

In the report, the off-shell electromagnetic pion form factors in the Bethe-Salpeter formalism are considered. The separable kernel of the first rank quark-antiquark interaction is used to solve the equation analytically. The half-off-shell pion form factors $F_1$ and $F_2$ , which are related to each other by the Ward-Takahashi identity, are calculated. The obtained off-shell form factors as well as static properties of the pion are compared with the results of other authors.

Speaker: Slautin, Mikhail (Dubna University/BLTP JINR)

Slautin_Baldin_ISHEPP_2025.pdf

15:20 The 12-th order QED corrections to lepton anomalies due to vacuum polarization insertions within the Mellin-Barnes representation

We investigate the contribution of the 12-th order QED corrections to the anomalous magnetic moment $a_L$ of a lepton $L$ ($L=e,~\mu$ and $\tau$) from diagrams with insertions of the photon vacuum polarisation operator consisting solely of purely lepton loops. The approach is based on consistent applications of dispersion relations for the polarisation operator and the Mellin-Barnes integral representation for propagators of massive particles. Explicit expressions for the radiative corrections to the anomalous magnetic moments from diagrams with five identical lepton loops in the polarisation operator are obtained, for the first time, as functions of the mass ratios $r = m_\ell/m_L$ of the loop lepton $\ell$ to the external lepton $L$ in the whole interval $0 < r < \infty$. The asymptotic expansions in the limits of both, small $r\ll 1$ and large $r\gg 1$, computed from the exact expressions are presented and the limit of their validity is investigated in detail. It is argued that in the intervals where the physical lepton mass ratios are located, the asymptotic expansions hold with an accuracy higher than the experimentally measured anomalies. Thus, these asymptotics, being much simpler in comparison with the exact, but lengthy expressions, are quite appropriate for practical numerical calculations of QED corrections to $a_L$ up to the desired accuracy.

Speaker: Dr Solovtsova, Olga (JINR & GSTU)

15:40 → 16:00 Coffee break

16:00 → 17:40 Relativistic heavy ion collisions

Convener: Dmitriev, Vadim (Saratov State University)

16:00 Baryon femtoscopy in 3.2 AGeV argon-nucleus interactions

A motivation for the baryon femtoscopy at the energy range of the experiment Baryonic Matter at the Nuclotron (BM@N) is discussed. The BM@M results on the proton-proton and proton-deuteron femtoscopy in the interactions of the argon beam of 3.2 AGeV kinetic energy with the C, Al, Cu, Sn, Pb targets are presented. The analysis procedure is described in detail. The dependence of the pp and pd correlation functions on the particle momentum in the pair rest frame has been obtained in the center-of-mass rapidity range of 0±0.6 and compared with the theoretical calculations. The fitted source size parameters are compared with the available data.

Speaker: Mr Alekseev, Petr (JINR, RRC KI)

AlekseevP.pdf

16:20 Search for anomalous leptons with masses in the range of 8-20 MeV at the Nuclotron (experiment proposal)

A scheme for searching for anomalous leptons using a
magnetic spectrometer based on drift chambers and an electromagnetic
calorimeter is considered. The design and characteristics of the detectors are given, as well as the results of tests in cosmic rays. An estimate of the masses of the presumed
particles is given.

Speaker: Shindin, Roman (JINR)

alepton_proposal.pdf

16:40 Measurements of Charged Fragments Spectators Yields in Xe+CsI reaction at 3.8 AGeV at BM@N

Charged fragment spectator yields were measured using the forward scintillation wall (ScWall) in Xe+CsI collisions at a xenon beam energy of 3.8 AGeV in the first physics run of the Baryonic Matter at Nuclotron (BM@N) experiment. The design and performance characteristics of the multichannel ScWall are presented. The yields of light charged spectator fragments produced in this reaction are obtained and compared with the results of DCM–QGSM–SMM model simulations.

Speaker: Volkov, Vadim (INR RAS)

17:00 MANIFESTATION OF ANISOTROPIC HYDRODYNAMICS BASED ON THE LATEST DATA ON PION AND KAON EMISSION IN HEAVY-ION COLLISIONS IN THE BM@N EXPERIMENT

A.T. D’yachenko$^{1,2}$

$^1$B.P. Konstantinov Petersburg Nuclear Physics Institute, National Research Center "Kurchatov Institute", Gatchina, Russia
$^2$Emperor Alexander I Petersburg State Transport University, St. Petersburg, Russia

In the BM@N collaboration experiment, double differential distributions of transverse momentum and rapidity of positively charged pions and kaons have recently been found for collisions of $^{40}$Ar ions with different targets at 3.2 GeV per nucleon [1]. The distributions of secondary particles in transverse momentum can be described using a Boltzmann distribution by fitting different temperatures at different rapidities [1]. One can say that the "transverse temperature" is approximately half the "longitudinal temperature".

In our opinion, this can be considered on the basis of anisotropic nonequilibrium hydrodynamics. In our works [2,3,4] a quantum nonequilibrium hydrodynamic approach is developed, in which the nonequilibrium state of the nuclear medium is described by a joint solution of the kinetic equation and the hydrodynamic equations. In works [3,4] we established a connection between the hydrodynamic equations and the effective Schrödinger and Klein-Fock-Gordon equations. In such an approach, many features of inclusive differential spectra of emitted secondary particles in heavy ion collisions can be described, including the cumulative effect [5,6]. In this description, the selection of the resulting hot spot is significant and an advantage was found in comparison with standard cascade calculations in describing the available experimental data.

In our nonequilibrium hydrodynamic approach applied to the data of [1], it turns out to be possible to represent the nucleon distribution function in the form depending on an ellipsoid in momentum space with semi-axes proportional to the longitudinal and transverse temperatures in the proper frame of reference. Thus, in accordance with the solution of the kinetic equation, the effective temperature can depend on the particle emission angle. Such anisotropic hydrodynamics with the selection of a hot spot is in agreement with the experimental data [1] for pions and kaons. Calculations using cascade models, as shown in [1], give an overestimated yield of kaons. The first comparison of our approach with experimental data obtained for the differential yields of protons, deuterons and tritons in the BM@N collaboration experiment [7] with the same nuclei as in [1] turned out to be quite successful.

1. Afanasiev S. et al. BM@N Collaboration, arXiv:2303.16243v4 [hep-ex] 8 Jun 2023
2. D’yachenko A.T., Gridnev K.A., Greiner W., J. Phys. G.$\bf{40}$, 085101 (2013).
3. D’yachenko A.T., Mitropolsky I.A.,Bull. Russ.Acad. Sci.: Phys., $\bf{88}$ , 1279 (2024)
4. D’yachenko A.T., Phys. At. Nucl. $\bf{87}$, 646 (2024).
5. D’yachenko A.T., Mitropolsky I.A., Phys. At. Nucl. $\bf{85}$, 1053 (2022).
6. D’yachenko A.T., Phys. At. Nucl. $\bf{87}$, 125 ( 2024).
7. Afanasiev S. et al. BM@N Collaboration, arXiv:2504.02759v1[hep-ex] 3 Apr. 2025

Speakers: Prof. D'yachenko, Alexander (Petersburg Nuclear Physics Institute of NRC "Kurchatov Institute" and Emperor Alexander I Petersburg State Transport University), D'yachenko, Alexander (Petersburg State Transport University)

Dyachenko A._ISHEPP_2025 (3)-1-1 (2).pdf

17:20 Strange hadron production in Au+Au collisions at √s_NN=3-27 GeV with UrQMD

The study of strange hadrons plays a critical role in understanding the properties of hot and dense
nuclear matter created in heavy-ion collisions, as they provide unique insights into the quantum chromodynamics phase transition and the possible formation of a quark-gluon plasma. Strangeness enhancement, first proposed as a signature of quark-gluon plasma, arises from the high production
rate of strange quarks in deconfined matter compared to hadronic interactions. Strange hadrons are particularly sensitive probes because of their relatively low production in ordinary hadronic collisions and their ability to retain information of the hadronization conditions.

In this work, the model dependence of strange hadron spectra (K0, Lambda, Xi, Omega) is studied with regards to the transverse momenta and different rapidities, collision centralities in the range of collision energies √s_NN = 3-27 GeV providing information on the dynamics of the hot dense matter on the onset of deconfinement. Precise measurements of strange particles yields in Au+Au collisions have potential to deepen our understanding of thermodynamic properties of the strangeness production and hadronization conditions near the phase boundary.

Speaker: Timofeev, Artem

Timofeev_ISHEPP2025.pdf

16:00 → 17:40 Structure functions of hadrons and nuclei

Convener: Arbuzov, Andrej (BLTP JINR)

16:00 Charge sum rules for quark fragmentation functions as a new manifestation of superconformal symmetry between mesons and baryons.

We have demonstrated that the charge sum rules for the quark fragmentation functions hold including simultaneously the contributions of mesons and baryons providing the conservation of the strangeness, electric and baryon charges. We also obtained the expression for the isospin conservation. The results are compatible to Gell-Mann–Nishijima formulas for quarks and hadrons manifesting a new aspect of quark-hadron duality.
Using our results, we formulated the constraints for the quark fragmentation functions to mesons π, K and baryons p, n, Λ. The numerical estimates based on some recent parametrizations of FFs confirm these constraints and also are in agreement with the truncated contributions to the charge and isospin sum rules.

Speaker: Dr Kotlorz, Dorota (BLTP JINR, Dubna, Russia)

kotlorz_baldin_26.pdf

16:20 Multipole Expansion for Electron-Nucleus Scattering at High Energies: An Overview

The multipole expansion for electron–nucleus scattering within the electromagnetic theory has proven highly effective as it provides detailed information about the structure of nuclei. However, at the high energies achieved by electron accelerators (about 105 GeV at CERN since 2000), both the weak and electromagnetic interactions should be considered simultaneously. This presentation introduces a multipole expansion for electron–nucleus scattering at high energies, developed within the framework of the unified electroweak theory. Nuclear multipole form factors (including electromagnetic, vector, and axial components) are calculated directly using the many-particle shell model and fractional parentage coefficients, avoiding the approximations adopted in earlier studies. This approach opens new prospects for exploring the electroweak interaction in complex systems and advancing the understanding of nuclear structure.

Speaker: Vo, Minh Truong

Seminar_JINR_09_2025.pdf

16:50 Simple models of PDFs and nPDFs

Speaker: Kotikov, Anatoly (JINR)

17:20 Ideal relativistic spin fluid model

Speaker: Obukhov, Yuri (Nuclear Safety Institute (IBRAE), Russian Academy of Sciences)

Obukhov_dubna25.pdf

Friday 19 September

09:00 → 10:30 Dynamics of multiparticle production

Convener: Baldin, Anton (JINR)

09:00 Gluon dominance model and multiparticle production

The gluon dominance model is developed to describe multiparticle production of secondary particles at high energies in lepton and hadron interactions, including annihilation processes and heavy quarkonium decays. According to this model, the multiparticle process is divided into two stages. The first stage describes the development of a quark-gluon cascade as a Markov branching process in the region of perturbation QCD. For the second stage, the transformation of quarks and gluons into observable hadrons (hadronization), a phenomenological scheme is proposed. It is universal and based on an experiment. The gluon dominance model demonstrates good agreement with data over a wide energy region.
It testifies that in hadron interactions valence quarks remain in the leading particles, and gluons are the sources of secondary hadrons. Quantitative estimates of the model parameters confirm the fragmentation mechanism of hadronization in leptonic interactions and the recombination mechanism in hadronic ones. The model description of the experimental distributions on the number of neutral pions in proton interactions at 50 GeV beams in the high multiplicity region are presented for the first time. It is shown that the main contribution to this region is made by gluon fission.

Speaker: Prof. Kokoulina, Elena (JINR)

Kokoulina_ISHEPP_2025.pdf

09:30 DD-pair production in the Parton Reggeization Approach within SPS and DPS scenarios

Open-charm production constitutes a stringent test of next-to-leading-order (NLO) perturbative QCD, because at the scale of charm quark $\mu \simeq m_c$ the strong coupling constant is already moderately small $\alpha_S \ll 1$. Single Parton Scattering (SPS) calculations alone fail to reproduce the measured DD-pair production. A realistic description may also include either gluon to charm-quark fragmentation or Double Parton Scattering (DPS) contribution [1,2]. The usage of gluon-to-charm fragmentation, however, includes double-counting issues and the limited range of validity of the gluon fragmentation function [3]. The detailed study in Ref. [1] investigated gluon fragmentation in both SPS and DPS, but charm quark mass effects were omitted. The first combined SPS and DPS predictions within $k_T$-factorization using Kimber-Martin-Ryskin (KMR) uPDFs were presented in Ref. [4].

In this work, we study DD-pair production in the Parton Reggeization Approach (PRA) [5]. PRA is basen on the Lipatov high-energy effective field theory [6] and the modified KMR unPDFs [7, 8]. The charm-quark mass effects in the $c\to D$ fragmentation are taken into account. We predict various differential cross sections for the SPS and DPS contributions to the DD-pair production in the central and forward rapidity regions at the LHC energies.

[1] R. Maciula, V. A. Saleev, A. V. Shipilova and A. Szczurek, New mechanisms for double charmed meson production at the LHCb, Phys. Lett. B 758, 458-464 (2016) doi:10.1016/j.physletb.2016.05.052.

[2] R. Maciula and A. Szczurek, Double open charm meson production at the LHC: new single- and double-parton scattering mechanisms, EPJ Web Conf. 130, 05013 (2016) doi:10.1051/epjconf/201613005013

[3] A. V. Karpishkov, M. A. Nefedov, V. A. Saleev and A. V. Shipilova, DbarD and DD pair production at the LHCb in the parton Reggeization approach, PoS DIS2016, 125 (2016) doi:10.22323/1.265.0125.

[4] A. van Hameren, R. Maciula and A. Szczurek,Production of two charm quark-antiquark pairs in single-parton scattering within the $k_t$-factorization approach, Phys. Lett. B \textbf{748}, 167-172 (2015) doi:10.1016/j.physletb.2015.06.061.

[5] M.A. Nefedov, V.A. Saleev, and A.V. Shipilova. Dijet azimuthal decorrelations at the LHC in the parton Reggeization approach. Physical Review D, 87(9):094030, 2013.

[6] L.N. Lipatov. Gauge invariant effective action for high energy processes in QCD. Nuclear Physics B, 452(1-2):369–397, 1995.

[7] M.A. Kimber, A.D. Martin, and M.G. Ryskin. Unintegrated parton distributions. Physical Review D, 63(11):114027, 2001.

[8] M.A. Nefedov and V.A. Saleev. High-energy factorization for the Drell-Yan process in $pp$ and $p\bar{p}$ collisions with new unintegrated PDFs. Physical Review D, 102(11):114018, 2020.

Speaker: Alimov, Lev (Samara University)

baldin2025_alimov_presentation.pdf

09:50 Exact Solutions in Kinetic Theory of the Vacuum Particle Production in SF QED and Graphene

In the theory of the vacuum particle creation in strong fields (Sauter-Schwinger effect) a small number of exactly solvable models acts as benchmarks [1]. In this respect, the nonperturbative kinetic theory methods also hold a prominent place. The analysis performed below is restricted by a class of the quantum kinetic equations of the Vlasov type in the strong electric fields (e. g., [2,3]).
The idea about connection between these methods of description of the quantum field systems in the states far from equilibrium was discussed long ago [4].
In the present work this connection is considered in details in the frameworks of the well-known approaches in the SFQED [5] and the graphene [6,7]. The both theories lead to the single-valued results in the cases of the model time dependent electric fields leading to the exact solutions of the problem, Such stability of the results is in a sense verification of the nonperturbative kinetic theory in
SFQED (in contrast with the alternative kinetic theory [8-10]).

References
1. E.S. Fradkin , D.M. Gitman , S.M. Shvartsman, Quantum Electrodynamics
with Unstable Vacuum, Springer-Verlag, Berlin, Germany (1991).
2. I. A. Aleksandrov, V. V. Dmitriev, D. G. Sevostyanov, S. A. Smolyansky
Eur. Phys. J. Special Topics, 229. 3469 (2020); arXiv:2004.02179 [hep-ph].
3. A. Fedotov, A. Ilderton, F. Karbstein, B. King, D. Seipt, H. Taya, G. Torgrimsson, Phys. Rep. 1010, 1 (2023).
4. Y. Kluger, E. Mottola, and J. M. Eisenberg, Phys. Rev. D 58, 125015 (1998).
5. A. A. Grib, S. G. Mamayev, V. M. Mostepanenko, Vacuum Quantum Effects in Strong Fields, Friedmann Laboratory Publishing; St.-Petersburg, Russia (1994).
6. G. L. Klimchitskaya and V. M. Mostepanenko, Phys. Rev. D 87, 125011 (2013).
7. S. A. Smolyansky, A. D. Panferov, D. B. Blaschke, and N. T. Gevorgyan, Particles, 3, 456 (2020).
8. S. P. Kim and C. Schubert, Phys. Rev. D 84, 125028 (2011).
9. Z. L. Li and Y. J. Li, Phys. Rev. D 110, 116029 (2024).
10. Z. L. Li, R. Z. Jiang, and Y. J. Li, arXiv: 2503.02530 [hep-ph].

Speaker: Smolyansky, Stanislav (Saratov State University)

Smolyansky-ISHEPP2.pptx

10:10 Particles production in ATROPOS string fragmentation model

The process of hadronization is usually seen as a universal process for all types of colliding particles and at all energies. A regular approach used in existing SoftQCD MC generators is to portray it as Lund quark-gluon string (QGS) fragmentation. However, results from both colliders and cosmic ray experiments indicate the need to transition to non-universal scheme of hadron production in order to describe the full set of data (the so-called Global Approach).

In this report I will present the first results of simulating multihadron production using ATROPOS MC generator. ATROPOS is a new hadronization model that implements the full potential of the Nambu-Goto string theory to derive the dynamics of the process of QGS fragmentation. An outstanding feature of the model is the consideration of the angular momentum of the QGS that allows one to break the universality of fragmentation by tuning the characteristic angular momentum of the string for different types of collision systems and at different energies to better reproduce the data.

The brief introduction into the basics of ATROPOS model is given. An importance of the angular momentum consideration for particle production is demonstrated. The results of simulating $e^+ e^-$, $pp$ and $\pi^-$C collisions are presented. The prospects of the new model are also discussed.

Speaker: Nikolaenko, Roman (MEPhI)

ISHEPP_Nikolaenko.pdf

Using the Virasoro conditions to revise the model of a quark-gluon string fragmentation

09:00 → 10:30 Projects NICA/MPD/SPD/BM@N at JINR

Convener: Finogeev, Dmitry (INR RAS)

09:00 Performance of the Vector Finder toolkit for track reconstruction at the BM@N experiment.

The Baryonic Matter at Nuclotron (BM@N) experiment at the NICA accelerator complex is currently in its active phase, analyzing data collected from the first physics run, and preparing for future data taking.

One of the most important software components for event reconstruction in high-multiplicity environment of heavy-ion interactions is a track reconstruction package. At BM@N, it was developed and implemented as a Vector Finder software toolkit, based on a constrained combinatorial search approach.

The current status of the method performance will be presented for simulated and real data from the BM@N experiment. Possible application of machine learning for method improvement (e.g. fake track suppression) will be discussed.

Speaker: Zinchenko, Dmitrii (JINR)

Zinchenko_Baldin_2025.pdf

09:20 Measurements of neutrons in the Xe+CsI reaction by the Highly Granular Neutron Detector prototype in the BM@N experiment

A Highly Granular time-of-flight Neutron Detector (HGND) is currently under development for use in the BM@N experiment to measure the yields and flow of neutrons with energies of 0.3–4 GeV [1]. The ratio of neutron to proton yields and the neutron-proton differential directed flow are sensitive to the contribution of symmetry energy to the equation of state of dense nuclear matter in Au-Au heavy ion collisions [2]. Such measurements in the BM@N experiment allow the equation of state (EoS) to be studied at a beam energy of 2.5-4A GeV, which is important for investigating the properties of astrophysical objects, such as neutron stars. Additionally, measuring the neutron energy spectra in projectile fragmentation enables estimation of the emitting source temperature [3].
To validate the concept of the full-scale HGND, a compact HGND prototype was constructed and tested in collisions of 3.8A GeV Xe with a CsI target at the BM@N experiment [4]. Neutron energy is reconstructed using the time-of-flight method individually in each cell. This configuration provides high neutron detection efficiency, good spatial resolution and time resolution of about 270 ps.
The HGND prototype was placed at 0 degrees to measure spectator neutrons and neutrons from electromagnetic dissociation (EMD). The reconstructed neutron kinetic energy spectra by time-of-flight are compared with the Geant4 modelling in the full geometry of the BM@N setup using the DCM-QGSM-SMM model and UrQMD-AMC model in Cascade mode and with Skyrme forces as heavy-ion collision generators and using the RELDIS model as EMD event generator. Neutron yields in the HGND prototype acceptance and cross-sections were obtained by correcting for model-estimated efficiencies for central and semi-central nuclear collisions and for EMD.

1. F. Guber et al., Experiment. Instrum. Exp. Tech., 67, 447–456
   (2024).
2. X.-X. Long, G.-F. Wei, Phys. Rev. C, 109, 054619 (2024).
3. P. Pawłowski et al., Phys. Rev. C, 108, 044610 (2023).
4. A. Zubankov et al., arXiv:2503.12624 [physics.ins-det] (2025).

Speaker: Zubankov, Aleksandr (Institute for Nuclear Research of the Russian Academy of Sciences)

baldin_Zubankov_2025.pdf

09:40 A novel method for neutron energy spectrum reconstruction with the HGND in the BM@N experiment

To extend the capabilities of the fixed-target BM@N experiment (JINR, Dubna), the Highly Granular Neutron Detector (HGND) [1] has been developed. This detector will enable unique measurements of neutrons in the kinetic energy range of 0.3-4.0 GeV. The HGND comprises two arms, each consisting of 8 layers of plastic scintillator with copper absorber plates in between. Each scintillation layer is assembled from an 11x11 matrix of individual cells, providing high spatial granularity and a time resolution of ~150 ps.
Neutrons have to be recognized in the presence of a high background of charged particles, secondary neutrons, and photons. A dedicated cluster identification algorithm is being developed to distinguish neutrons from background particles. The neutron kinetic energy is reconstructed via the time-of-flight technique. The first results of neutron energy spectrum reconstruction in Bi+Bi collisions at 3A GeV will be presented.

References:
1. S. Morozov et al., Nucl.Instrum.Meth.A 1072, 170152 (2025)

Speaker: Shabanov, Arseniy (INR RAS)

Shabanov_NovelMethodHGND.pdf

10:00 Graph Neural Network-based Neutron Reconstruction in the HGND at the BM@N experiment

The Highly Granular Neutron Detector (HGND) is designed for the BM@N experiment, aimed at investigating neutron emission in heavy ion collisions at beam energies of up to 4A GeV. The HGND allows the identification of neutrons and the reconstruction of their energies using time-of-flight method, which is crucial for analyzing neutron yields and azimuthal flow. Given the challenging energy range of $0.5-4$ GeV and the significant background contributions in the BM@N environment, the development of advanced reconstruction algorithms is essential. In this contribution, we present a graph neural network approach to the neutron reconstruction problem and discuss the preliminary results of the proposed algorithm and effects for the physics performance.

Speaker: Bocharnikov, Vladimir (HSE University)

VB_Baldin25.pdf

09:00 → 10:30 Relativistic heavy ion collisions

Convener: Prof. Melezhik, Vladimir (BLTP JINR Dubna)

09:00 Transverse Momentum Spectra of Hadrons in the Blast-Wave Model with Local Equilibrium and Tsallis Statistics with Global Equilibrium

In this study, we calculate the transverse momentum distributions of hadrons using two frameworks: the finite-volume blast-wave model under local equilibrium and the Tsallis-3 statistics model under global equilibrium. To implement the local equilibrium model, we analyzed the relativistic Planck and Ott transformations for thermodynamic quantities. The Planck transformations are derived from the conjugate fundamental thermodynamic potential, specifically the negative Lagrangian, with velocity as an independent state variable. In contrast, the Ott transformations, derived from the total relativistic energy as a function of velocity, face a theoretical limitation, as this energy does not qualify as a true thermodynamic potential. We developed consistent Boltzmann-Gibbs and Tsallis blast-wave models for finite-volume freeze-out firecylinders in heavy-ion collisions, incorporating Planck and Ott transformations to determine temperature and chemical potential in the laboratory reference frame $K$. Comparative analysis of local and global equilibrium models shows that Planck transformations yield consistent transverse momentum distributions, whereas Ott transformations exhibit significant discrepancies. Applying the Boltzmann-Gibbs blast-wave model with Planck transformations, we successfully described the experimental transverse momentum spectra of charged pions produced in heavy-ion collisions at high energies.

Speaker: Dr Parvan, Alexandru (JINR and IFIN-HH)

parvan_2025_Baldin_conf.pdf

09:30 Collective flow of lambda hyperons in the MPD experiment at NICA energies

Collective flow measurements are essential for studying the strongly-interacting matter formed in relativistic heavy-ion collisions. Lambda hyperons serve as unique probes due to their strangeness, offering distinct sensitivity to partonic collectivity and hadronization mechanisms compared to lighter particle species. This study investigates the directed and elliptic flow of lambda hyperons in Xe+Xe collisions at center-of-mass energy 2.87 GeV generated with the UrQMD model. The results are necessary for the analysis of the upcoming experiment with the MPD detector.

Speaker: Troshin, Valery (JINR)

Collective flow of lambda hyperons in the MPD experiment at NICA energies.pdf

09:50 Parton energy loss in Cu+Au and U+U collisions at √s_NN=200 and 193 GeV, respectively

In relativistic heavy ion collisions, a dense hot matter called quark-gluon plasma (QGP) is formed [1]. Information about the properties of formed medium can be obtained from data on the energy loss of quarks and gluons (partons) with high transverse momenta $p_{T}≫Λ_{QCD}$ produced in hard parton-parton interactions [2]. The energy loss of partons in QGP leads to the jet quenching effect in nucleus-nucleus collisions [2], which is studied experimentally based on data on hadron yields.

One of the most important experimental quantities related to the parton energy loss in the QGP is the fractional parton energy loss $S_{loss}$, which is defined as the ratio of the average parton energy loss $∆E$ to their average initial energy $E_{in}$ [2,3]. The suppression of hadron yields at high $p_T$ caused by the energy loss of parent partons is characterized by the nuclear modification factor $R_{AB}$ [2,3]. Therefore, using the relationship between $S_{loss}$ and $R_{AB}$ [3], the dependence of $S_{loss}$ on the hadron transverse momentum $p_T$ and the collision centrality (the number of participating nucleons $N_{part}$) can be obtained. The azimuthal anisotropy of hadrons produced in heavy ion collisions relative to the reaction plane (the plane formed by the beam axis and the impact parameter vector) in the intermediate rapidity region ($|η|<0.35$) is quantitatively characterized by the elliptic flow $v_2$ [4]. Based on the previously obtained values of $v_2$ of hadrons at $p_T > 5 GeV/c$, it is possible to calculate the dependences of the $S_{loss}$ value on the azimuthal angle $Δφ$ [3] of hadrons (in particular $π^0$) emission which allows to study the anisotropy in the distribution of the QGP characteristics. For all values of $N_{part}$ and $Δφ$, the effective parton path-length $L_{eff}$ was calculated using the Glauber model [5], considering the distribution of the color charge density in the QGP, the time dependence during the longitudinal expansion of QCD matter, and the distribution of parton creation points.

In this work, the values of the fractional parton energy losses depending on the azimuthal angle of π0 emission $S_{loss}(Δφ)$ and the effective parton path-length $S_{loss}(L_{eff})$ were obtained for different values of $N_{part}$ and $p_T$ in Cu+Au and U+U collisions at $\sqrt{s_{NN}}=200$ GeV and $193$ GeV, respectively.

The results of the work can be expanded for use in the MPD and SPD experiments at the NICA collider.

We acknowledge support from the Ministry of Science and Higher Education of the Russian Federation, state assignment for fundamental research (code FSEG-2025-0009).

1. Adcox K. et al., Nuclear Physics A 757, 184-283 (2005).
2. Enterria, D., Nuclei and Atoms, 471-520 (2010).
3. Adler S.S. et al., Phys. Rev. C 76, 034904 (2007).
4. Voloshin S.A., Poskanzer A.M., Snellings R., Z. Landolt-Bornstein 23, 293–333 (2010).
5. Dainese A., Loizides C., Paic G., Eur. Phys . J. C 38, 461–474 (2005).

Speaker: Mr Borisov, Ivan (Peter the Great St. Petersburg Polytechnic University)

Sloss_Borisov_ENG_16x9.pdf

10:10 Directed, elliptic and triangular flow of charged hadrons in O + O, Kr + Kr and Xe + Xe collisions at \sqrt{s_{NN}}$ = 6 GeV in UrQMD model for SPD experiment

Understanding the properties of Quark-Gluon Matter (QGM) at high baryon densities is essential for mapping the QCD phase diagram, probing the equation of state of dense nuclear matter, and shedding light on the structure of neutron stars and the evolution of the early universe. At high baryon potential, theoretical calculations of QCD become sophisticated and unstable. Therefore, the study of QGM in heavy-ion collisions in this energy region is an important task, since it allows determining QGM properties. One of the most important observables is azimuthal anisotropy, the measurement of which provides information on the transport properties and the equation of state of the created matter. To study azimuthal correlations, the single-particle distribution in $\phi$ is expanded in a Fourier series where the coefficients $\upsilon_{n}$ before each term are called the coefficients of the collective flow. Coefficients $\upsilon_{1}$, $\upsilon_{2}$ and $\upsilon_{3}$ correspond to directed, elliptic and triangular flow.

This work is devoted to the study of directed, elliptic and triangular flow of charged hadrons in O + O, Kr + Kr and Xe + Xe colisions at $\sqrt{s_{NN}}$ = 6 GeV from UrQMD model, as part of preparations for the SPD experiment at NICA. The results will serve as theoretical input for interpreting future SPD data.

Speaker: Povarov, Alexey (NRNU MEPhI)

aspovarov_baldin_seminar_2025_pres_final.pdf

10:30 → 10:50 Coffee break

10:50 → 12:50 Dynamics of multiparticle production

Convener: Prof. Кокоулина, Елена (JINR)

10:50 Charmed particle production in nucleus-nucleus interactions in Geant4 FTF model

Some predictions on D-meson production in soft proton+proton, 2H+2H and 4He+4He interactions at √S=10 and 20 GeV are given for future SPD/NICA experiment using Geant4 FTF model. Essential details of implementation of charmed particle production in the FTF model are considered. Results of model calculations of kinematical properties of the particles produced in hadron-hadron interactions in a comparison with corresponding experimental data are presented.
Recently, the NA61/SHINE collaboration has published preliminary experimental data on D0 and anti-D0 meson production in central Xe+La interactions at √S=16.8 GeV. The collaboration has compared the data on charmed particle production with predictions of various Monte Carlo models. It turned out that none of the models described the experimental data. To check the FTF model, we have compared the model calculations with the NA61/SHINE experimental data. We show Geant4 FTF model prediction for D0 and anti-D0 meson production is close to other model predictions (without QGP formation) and below the experimental data. We believe that the experimental results show enhanced production of charmed particles in nucleus-nucleus interactions.

Speaker: Dr Galoyan, Aida (LHEP JINR)

Charm09_25U.ppt

11:10 Bose–Einstein Correlations of Charged Pion and Kaon Pairs at RHIC Energies Using the UrQMD and SMASH+vHLLE Models

Two-particle femtoscopy via Bose–Einstein correlations (BEC) provides direct access to the space–time structure of particle-emitting sources in relativistic heavy-ion collisions. In this study, we present a systematic analysis of BEC for identical charged pion and kaon pairs in Au+Au collisions at Relativistic Heavy Ion Collider (RHIC) energies. Model calculations were performed using the purely hadronic transport approach of the Ultrarelativistic Quantum Molecular Dynamics (UrQMD) model and the hybrid SMASH+vHLLE framework, which combines viscous hydrodynamics with a hadronic afterburner.

Correlation functions were constructed in the longitudinally co-moving system (LCMS) and fitted assuming a Gaussian source to extract femtoscopic radii ($R_\text{out}$, $R_\text{side}$, $R_\text{long}$) and correlation strengths. The beam energy, pair transverse momentum, and centrality dependencies of these radii are compared between the models and with available experimental data from the STAR Collaboration. The results demonstrate the sensitivity of $R_\text{out}/R_\text{side}$ and $R_\text{out}^2 - R_\text{side}^2$ to the underlying collision dynamics, in particular to the presence or absence of a hydrodynamic phase. Differences between pions and kaons highlight the role of hadronic rescattering and resonance decays in shaping the femtoscopic observables.

Our findings contribute to ongoing efforts to constrain the space–time evolution of the medium created in heavy-ion collisions and to probe the nature of the QCD phase transition at RHIC energies.

Speaker: Korobitsin, Artem (Joint Institute for Nuclear Research, National Research Nuclear University MEPhI)

Korobitsin_BaldinSeminar2025.pdf

11:30 Negative binomial distribution in multiparticle production and fractal dimension of black body

A modern definition of New Physics is proposed.
A correction to the W-boson mass is calculated.
A modern definition of New Physics is proposed.
A correction to the W-boson mass is calculated.
A method for measurement of the fractal dimension for the blackbody derived.
Necessary conditions for existence of the bound states in extended quantum mechanics [1] obtained.
Complex, quaternion and octonion extensions of hydrodynamics considered.
A connection is established between the negative binomial distribution (NBD) for semi-inclusive distributions and the Hagedorn distribution.
A connection is established between the NBD and the Riemann zeta function on critical axes.
Candidates for non-Riemannian zeros of the zeta function proposed in [2] are verified by direct calculations.

[1] Makhaldiani N. New Hamiltonization of the Schrodinger Equation by Corresponding Nonlinear Equation for the Potential, JINR Communications E2-2000-179, Dubna, 2000.
[2] Н.В.Махалдиани, НОВАЯ ФИЗИКА, МАССА W-БОЗОНА,ПОЛУИНКЛЮЗИВНЫЕ РАСПРЕДЕЛЕНИЯ И НУЛИ ЗЕТА-ФУНКЦИИ,
ФИЗИКА ЭЛЕМЕНТАРНЫХ ЧАСТИЦ И АТОМНОГО ЯДРА,
2025.Т.56,вып.2.C.403–413

Speaker: Makhaldiani, Nugzar (JINR)

Makhaldiani, Baldin seminar 2025 talk2.pdf

12:00 K-mesons production and isospin-symmetry in $pp$ and $AA$ collisions

The production of $K$ mesons in $pp$ and $AA$ collisions at high energies is analyzed. We show that the ratio $R_K~=~\frac{\sigma_{K^+}+\sigma_{K^-}}{2\sigma_{K^0_S}}$ calculated within the similarity approach [1] and using the Lund model in the form of MC generator PYTHIA [2] is above 1 even at the conservation of the isospin-symmetry. It is about 1.18 at $\sqrt{s}=$11.9 GeV (the NA61/SHINE data [3]) and it decreases up to 1, when the energy increases up to a few TeV (ALICE data). The reason of this is related to the dynamics of the kaon production. This energy dependence of $R_K$ practically does not depend on the sort of beam or target.

Our calculations do not contradict to the world data at $\sqrt{s}=$ 6-40 GeV and $\sqrt{s}=$ 3 TeV. In the energy region 40 GeV $<\sqrt{s}<$ 200 GeV there is an excess of the STAR data, having too large error bars, over our calculations. Therefore, it is desirable to check the isospin-symmetry violation by improving the measurement accuracy.

References
[1] G.I. Lykasov, A.I. Malakhov, A.A. Zaitsev, Eur.Phys.J.A 60, 239 (2024).
[2] T. Sjoestrand, Comp. Phys. Commun, 82, 4 (1994).
[3] The NA61/SHINE Collaboration, F. Giacosa, M. Gorenstein,R. Poberezhniuk,S. Samanta, Nature Communications, 16, 2849 (2025). arXiv:2312.06572v6 [nucl-ex].

Speaker: Lykasov, Gennady (JINR)

GLMZ_19.9.25__corr_MZ(1).pdf

10:50 → 12:50 Nuclear astrophysics

Convener: Dr Parvan, Alexandru (JINR and IFIN-HH)

10:50 Threshold amplification of X(a,b)Y reactions: from muon-catalyzed fusion to electromagnetic formfactors of hyperons

Deviation of the cross section for the nuclear reaction X(a, b)Y from the Gamow formula due to an interaction additional to the Coulomb one in the entrance channel has been analyzed[1]. It is shown that the reaction cross section has an oscillating structure at low energies. If the maximum of the first oscillation is close to the threshold of the channel a+X, it has a resonance behavior[2]. To analyze the effect, simple relations between the period and the amplitude of the oscillations with parameters of the interaction have been derived. Specifically, they predict the cross-section oscillations of fusion (or muon-catalyzed fusion) reactions of the type X(a,b)Y for slow collisions between nuclei (a) and atomic target (X), as, for example, the reaction D(d,p)T between deuterons (d) and deuterium atoms (D)[2]. Similar behavior we also observed in muon-catalyzed fusion collisional reactions pμ + p and tμ + d[2].
Recently, we have extended the formalism developed in [2] for descriptions of the cross section of Λ-hyperon production in e+ e- collisions at high energies, obtained by the BESIII Collaboration [3]. The application of this formalism to the analysis of electromagnetic form factors is also discussed.

[1] L.N. Bogdanova et. al. Sov. J. Nucl. Phys. 34, 662 (1981); Phys. Lett. B115, 171 (1982).
[2] V.S. Melezhik, Nucl. Phys. A550, 223 (1992)
[3] M. Ablikim et. al.Phys. Rev. Lett. 131, 191901 (2023)

Speaker: Melezhik, Vladimir (BLTP JINR Dubna)

melezhik-BALDIN-2025.pdf

11:20 Strangelet Searches from Neutron Stars and Binary Mergers with Current and Future Observatories

Supernova remnants and compact binary mergers are prime candidates for Galactic cosmic‑ray acceleration. We have evidence that HESS J1731-347 and GW170817 have the capacity to accelerate hadrons to TeV energies and could potentially harbor strange quark matter (SQM), thereby inspiring a quest for strangelets. A transition from the 2SC to CFL phase in quark matter could release strangelets whose annihilation or decay leaves distinct imprints in cosmic rays and VHE gamma rays. Using H.E.S.S., HAWC and Fermi-LAT data and forecasting for CTAO, we model strangelet‑induced spectral features, derive the implied strangelet properties, and quantify CTAO's ability to detect or constrain them.

Speaker: Dr Das, Chitta Ranjan (BLTP, JINR)

crdas_baldin.pdf

11:50 Magnetorotational supernova neutrino spectra vs mass ordering

The dynamics of neutrinos in hot and dense magnetized stellar material, corresponding to magnetorotational supernova explosion, is considered. It is shown that taking into account fluctuations in the interaction of neutrinos with matter leads to the Fokker-Planck equation for the dynamics of the distribution function in the phase space. The component of the kinetic equation additional to the transfer effect [1] is determined by straggling in neutrino collisions in a magnetized nucleon gas due to the Gamow-Teller neutral current interaction. The effect of fluctuations leads to an additional increase in the hardness of the neutrino spectra. The effects of neutrino oscillations in magnetic field and dense matter on detection by the KM3NeT and Baikal-GVD observatories are discussed. It is shown that the applications of the k-fold coincidence technique in data processing makes it possible to increase the upper limits of the distance for the observation threshold by a factor of 1.5√k.
1. Kondratyev V. N. Magnetorotational Supernova Neutrino Emission Spectra and Prospects for Observations by Large-Size Underwater Telescopes // Phys. At. Nucl. – 2023. – V. 86. – P. 1083-1089.

Speaker: Kondratyev, Vladimir (BLTP JINR)

VKoHEPP25P.pdf

12:10 Neutron Stars with Λ- and Ξ-Hyperons with Skyrme Potentials: Correlations and a Parametrization for the Maximum Mass

The softening of the equation of state of the neutron star matter upon the inclusion of hyperons, leading to a reduction in their maximum mass below the limit established by observations, named "hyperon puzzle" remains one of unresolved problems in the nuclear astrophysics. This work investigates the structure of neutron stars within the Skyrme approach. In contrast to previous studies within this framework, we include not only Λ-hyperons but also Ξ-hyperons in our consideration. A wide variety of parameters for nucleon-nucleon and hyperon-nucleon interactions is examined. Calculations of the macroscopic characteristics of neutron stars, including mass, radius, and tidal deformability, have been performed.

We study correlations between neutron star characteristics and potential properties, reflecting their sensitivity to the dynamics of baryonic interactions. A simple approximate relationship is proposed to estimate the neutron star maximum mass from the characteristics of baryonic interactions. The influence of Ξ-hyperons on the possible ranges of observable quantities is also demonstrated.

Speaker: Nasakin, Artur (Faculty of Physics, Moscow State University)

Dubna2025.pdf

Dubna2025.pptx

10:50 → 12:50 Projects NICA/MPD/SPD/BM@N at JINR

Convener: Shabanov, Arseniy (INR RAS)

10:50 The Highly Granular Time-of-Flight Neutron Detector for the BM@N experiment

The Highly Granular Neutron Detector (HGND) is being developed for the BM@N (Baryonic Matter at Nuclotron) experiment on the extracted beam of the Nuclotron (JINR, Dubna). The HGND will be used to measure the neutron yields in energy range 300 – 4000 MeV as well as azimuthal asymmetry of neutron flow in nucleus-nucleus collisions at beam energies of 2–4 AGeV. At these energies, nuclear density reaches 2–4 times the normal value, comparable to conditions during merging of neutron stars. The dependence of the equation of state of dense nuclear matter on the term characterizing the isospin (proton-neutron) asymmetry of nuclear matter will he studied using the HGND.
The HGND consists of two arms, each containing 8 layers of plastic scintillator arrays with copper absorber plates in between. Each scintillation layer is composed of an 11×11 matrix of individual cells with size 40×40×25 mm³ equipped with an individual light readout using EQR15 11-6060D-S photodetectors.
Currently, one fully assembled scintillator layer of the HGND with 33 readout channels has been constructed. This prototype layer matches the final detector design, featuring a readout system with developed 100 ps FPGA-based TDC (Time-to-Digital Converter), a time synchronization system based on White Rabbit, and FEE (Front-End Electronics) control. Performance tests demonstrate a channel time resolution of ~150 ps and confirm integration compatibility with BM@N readout and control systems.
Details of the detector design, development status, and performance studies will be presented.

Speaker: Finogeev, Dmitry (INR RAS)

HGND_Finogeev_Bald2025.pdf

11:10 Development of a New Silicon Tracking Station for the BM@N Hybrid Tracker

A new silicon tracking station has been developed and implemented as part of the upgrade of the BM@N experiment’s tracking system at the Nuclotron, aimed at studying heavy-ion collisions. The station is based on CBM-BM@N–type double-sided silicon microstrip modules equipped with high-rate streaming readout electronics using STS-XYTER chips. Signal routing is realized via ultra-lightweight (0.23% X₀) flexible aluminum cables connected through TAB bonding (Tape Automated Bonding).
Performance of the modules was validated in a series of beam tests at the SC-1000 accelerator (PNPI, Gatchina), demonstrating a spatial resolution of 15.4 µm, a signal-to-noise ratio above 21, and a detection efficiency of 99% for 1 GeV protons. The system is capable of operating at trigger rates up to 78 kHz and occupancies up to 360 kHz·s⁻¹·cm⁻².
The station consists of six modules mounted on a low-mass fiberglass frame, located 7 cm downstream of the target, and operates in conjunction with FwdSi and GEM detectors to provide high-precision track reconstruction. Integration with the BM@N data acquisition system is achieved using FPGA-based data buffering and real-time event selection within a configurable trigger window.

Speaker: Dementev, Dmitrii (JINR LHEP)

Dementev_Baldin_2025.pdf

11:30 Status of the Electromagnetic Calorimeter Testing for the MPD Experiment at the NICA Collider

The Electromagnetic Calorimeter (ECal) is designed to measurement position, energy and time of flight of photons and electrons in heavy-ion collisions. This report presents the status of ECal testing for the Multi-Purpose Detector (MPD) at the NICA collider.

Speaker: Baryshnikov, Victor (JINR)

Baldin2025PresentationBaryshnikov.pdf

11:50 TPC Tracking for the MPD Experiment

Full chain track reconstruction in TPC detector for the real experiment is presented. Three necessary components: native TPC geometry, fast multithreaded clustering and ACTS tracking were implemented to work together to achieve the future goal of superior performance in tracking efficiency and computational speed. Preliminary performance benchmarks in mass production simulations will be demonstrated.

Speaker: Hnatic, Slavomir (JINR)

TPC_tracking_for_MPD_Experiment.pdf

12:10 Electron Identification using Machine Learning in the MPD Experiment at NICA

The Multi-Purpose Detector (MPD) experiment is a flagship heavy-ion experiment of the NICA facility at JINR, in Dubna expected to start operation in 2026. The experiment will operate in the energy range $\sqrt{s_{\rm NN}}$ = 4-11 GeV in collider mode and $\sqrt{s_{\rm NN}}$ = 2.4-3.5 GeV in fixed-target mode which covers the high net-baryon density region of the QCD phase diagram.

Particle identification plays a critical role in experimental data analysis, in particular, electron identification which is essential for measuring dileptons in heavy-ion collisions. Traditional methods based on one-dimensional selection criteria often suffer from loss of efficiency due to multiple sequential selection cuts on discriminating variables. In this presentation, we discuss the application of machine learning techniques to enhance electron identification in the MPD experiment. Classifiers were trained on electron samples, and their performance was evaluated and compared to that of the conventional cut-based approach. The results demonstrate the potential of machine learning to significantly improve electron identification efficiency while maintaining an almost 100% purity.

Speaker: Dr Rode, Sudhir Pandurang (Joint Institute For Nuclear Research, Dubna, Russia)

ML_eID_SPRode_BaldinSeminar_Sep2025.pdf

12:30 Tasks and status of Forward Hadron Calorimeter at MPD

This work discusses the current status of the Forward Hadron Calorimeter (FHCal) at MPD/NICA as its launch approaches. The main goal of FHCal is measurement of geometry of interaction by estimating of centrality and reaction plane orientation. Each arm of the FHCal will comprise 44 heterogeneous modules, and one of these arms has already been assembled in Dubna. A brief overview of the detector's current state will be provided. We have now focused on integration of the FHCal into the MPD detector. This integration process includes the development of a patch panel to streamline the separation of all FHCal cabling from the MPD system and enhance modularity. A developed simultaneous energy calibration method for the FHCal modules using cosmic muons, on a fully assembled FHCal arm will soon be tested. Preliminary tests on a small array of modules show that compared to a more traditional calibration method reliant on horizontal muons, our approach demonstrates good agreement in light collection efficiency. However, challenges arise due to the heterogeneous structure of the calorimeter, which complicates the reliability of muon tracks orthogonal to the module axis.

Speaker: Strizhak, Alexander (INR RAS)

Status_FHCal_sep_2025.pdf

12:50 → 14:00 Break

14:00 → 15:40 Dynamics of multiparticle production

Convener: Мусульманбеков, Женис (JINR, LIT)

14:00 The development of the ideas of A.M.Baldin on description of multiparticle production in relativistic nuclear collisions based on the properties of the Lobachevsky space

The notion of an elementary particle proposed by A.M.Baldin and the ideas of examination of multiple particle production in the space of relative velocities are considered. The transition to the space of relative rapidities (the Lobachevsky space) is substantiated. The connection between the fundamental distance in the rapidity space following from the properties of the Lobachevsky geometry and the size of the proton is examined. The structure of the directed nuclear radiation is described based on the experimental bubble chamber data. The method for separation of collective flows (jets) in multliparticle production is proposed on the basis of relativistically invariant description of relative distances in the rapidity space.

Speaker: Baldin, Anton (JINR)

14:30 Self-similarity method in relativistic nuclear physics

The self-similarity approach is used to describe particle production in relativistic particle collisions. The results are based on analysis of the vast experimental material obtained with the bubble chambers. The asymptotic properties of particle production which are intrinsically connected with the properties of the Lobachevsky geometry are demonstrated. It is stated that the Lobachevsky space is the most suitable space for description of relativistic systems.
The specific features of description of inclusive spectra of secondary particles based on the self-similarity solution for cumulative and subthreshold reactions in relativistic nuclear collisions are considered. The transition from non-cumulative to cumulative processes is considered on the basis of experimental data.
The considerations on the role of soft processes in experiments at the accelerator complex NICA are given.

Speaker: Baldina, Elina (JINR)

15:00 Application of Differential Geometry Methods for Analyzing Experimental Data on Multiple Particle Production in Relativistic Nuclear Physics

An analysis of the geometric properties of rapidity space (Lobachevsky hyperbolic space) in multiple particle production is presented. Experimental data obtained using bubble chambers were analyzed using differential geometry methods. Bimodal angular distributions at nucleon interaction energies of 1.5–10 GeV were examined, indicating a transition from Euclidean to hyperbolic geometry starting at nucleon interaction energies of 3–5 GeV.

Speaker: Ponomareva, Anastasia (JINR)

14:00 → 15:40 Relativistic heavy ion collisions

Convener: Dr Kireyeu, Viktar (JINR)

14:00 Forward neutrons from 12C-12C and 40Ca-40Ca collisions in the SPD experiment as a probe of nucleon-nucleon correlations.

The research program of the SPD  experiment at NICA facility is focused on studies of collisions of polarized protons and deuterons [1,2]. Studies of collisions of non-polarized light nuclei, 12C and 40Ca, are also considered as a possible extension of the SPD research program [3]. The SPD setup will be equipped with a pair of Zero Degree Calorimeters (ZDC) for luminosity measurements and local polarimetry with forward neutrons. In studies of 12C-12C and 40Ca-40Ca collisions, ZDC can be employed to detect forward spectator neutrons as event triggers and determine the collision centrality. However, as it was demonstrated [4], the short-range nucleon-nucleon correlations in colliding nuclei can significantly change the yields of the spectator neutrons. It was also shown that accounting for intranuclear clustering decreases the yield of spectator neutrons [5].
In this work, 12C-12C and 40Ca-40Ca collisions at the SPD were simulated with the Abrasion-Ablation Monte Carlo for Colliders (AAMCC-MST) model with MST-clustering [4-7], which was validated for fragmentation of 16O [5,6]. In order to study the effect of α-clustering in 12С, the nuclear density profile of 12С was parametrized either as three α-clusters arranged into a triangle [8] or by the harmonic oscillator parametrisation. The short-range nucleon-nucleon correlations (SRC) in 12C and 40Ca were taken into account following Ref. [9]. The yields of forward spectator neutrons were calculated for 12C-12C and 40Ca-40Ca collisions at √sNN = 11 GeV. The centrality dependence of the neutron yields was proposed as a possible probe of the SRC in 40Ca and α-clustering in 12C. The obtained results can help in evaluating the performance of neutron ZDCs in future nucleus-nucleus runs at the SPD.

References

[1] V. Abazov et al., (SPD Collaboration), Natural Sci. Rev. 1, 1 (2024)
[2] V. Abazov et al., (SPD Collaboration), arXiv:2102.00442 (2021)
[3] V. Abramov et al., Phys. Part. Nucl. 52, 1044 (2021)
[4] N. Kozyrev et al., Eur. Phys. J. A 58, 184 (2022)
[5] A. Svetlichnyi et al., Physics 5, 381 (2023)
[6] A. Svetlichnyi et al., Phys. Atom. Nucl. 85 985 (2022)
[7] R. Nepeivoda et al., Particles 5, 40 (2022)
[8] W. von Oertzen et al., Phys. Reports 432, 43 (2006)
[9] M. Alvioli et al., Phys. Rev. Lett. B 680, 225 (2009)

Speaker: Svetlichnyi, Aleksandr (MIPT, INR RAS)

Svetlichnyi_Clustering.pdf

14:20 Target dependence of fragmentation reaction cross-sections at intermediate energies and its calculation in the relativistic and low-energies oriented models.

In the year 1971 the pioneering works on fragmentation reactions in the collisions at relativistic energies began. At the same time in experiments at low energies deep- inelastic mechanism was discovered. To describe the fragmentation reactions at relativistic energies different models such as the EPAX and the Abrasion–Ablation models were developed. As the experiments on projectile fragmentations at low-energy were continued it was observed that beginning from the energies of about 30 MeV per nucleon direct processes began to prevail. Due to this to plan the experiments at low and intermediate energies the EPAX, the Abrasion–Ablation models and other models common in describing relativistic nuclear collisions were used. It was shown that these models describe quite well the cross-sections of fragments not far from the stability-line also at low energies.
But what these models cannot predict is the ratio of fragments cross-sections produced in the reactions with the same projectile but different targets, called target ratio. In this report we analyze the target ratio values
in the reactions with different projectiles from 18O to 48Ca with energies from 35 to 140 MeV per nucleon on two targets : 181Ta and 9Be. The results of calculations in the modified transport-statistical approach, developed by our group, the EPAX, Abrasion–Ablation and the FRACS models and comparison to the experimental data are presented. The hyperbolic shape of the envelope of target ratio values is explained as manifestation of the different range of impact parameters involved in reactions on heavy and light targets.

Speaker: Mikhailova, Tatjana (LIT, JINR)

ISHEPP_TMikh.pdf

14:40 Addressing heavy ion collision parameters estimation challenges via neural network techniques

This work focuses on the challenge of estimating multiple parameters in heavy-ion collisions using data-driven techniques [1-3]. A significant difficulty arises from the dependence of algorithm accuracy on the choice of event generator models such as QGSM [4], EPOS [5], and PHQMD [6], which introduce biases affecting parameter reconstruction.

We evaluated several approaches to mitigate these biases, starting with classical methods like principal component analysis (PCA) and naive training on combined datasets from different generators. Then, we explored neural network-based methods, including deep reconstruction networks [7], which demonstrated superior robustness and accuracy.

The best-performing models achieved accuracy comparable to those trained on single-generator data, while improving over naive mixed-dataset training. These findings suggest that advanced neural network techniques can help overcome generator-induced biases, supporting the development of generalized algorithms for reliable estimation of heavy-ion collision parameters.

The authors acknowledge Saint-Petersburg State University for a research project 103821868

[1] A.A.Baldin, G.A. Feofilov, P. Har'yuzov, and F.F. Valiev, // Nucl. Instrum. Meth.A 2020, V.958, P.162154. https://doi.org/10.1016/j.nima.2019.04.108
[2] https://nica.jinr.ru/
[3] K.A. Galaktionov, V.A. Roudnev, and F.F. Valiev, Moscow Univ. Phys. Bull. 78 (2023) Suppl 1, S52-S58
[4] Amelin N. S., Gudima K. K., Toneev V. D., Sov. J. Nucl. Phys. 1990. V. 51(6), P. 1730-1743
[5] Werner, Klaus and Liu, Fu-Ming and Pierog, Physical Review C 2006, V. 74
[6] Aichelin, J. and Bratkovskaya, E. and Le Fèvre, A. and Kireyeu, V. and Kolesnikov, V. and Leifels, Y. and Voronyuk, V. and Coci, G., Physical Review C 2020, V. 101
[7] Wang, M. and Deng, W. Neurocomputing, 2018, V. 312, P 135-153

Speaker: Galaktionov, Kirill

Galaktionov_Slides.pdf

15:00 Collective flow harmonics correlations analysis for model data at Nuclotron-NICA energies

A primary objective of relativistic heavy-ion collision beam energy scan programs is to explore the high-density equation of state (EoS) and potential phase transitions in dense baryonic matter. Anisotropic flow measurements, defined from the azimuthal distributions of final-state charged particles, offer a powerful tool to extract such information. The correlations between different flow harmonics can impose even stronger constraints on the EoS parameters and provide further understanding of the underlying flow formation dynamics. This study investigates the correlations among the directed flow (v1), elliptic flow (v2), triangular flow (v3), and quadrangular flow (v4) using a state-of-the-art heavy-ion collision model for the Nuclotron-NICA energy range, which is critical for the upcoming MPD experiment. The model predictions are compared against existing HADES experimental data.

Speaker: Bikmetov, Niktia (JINR)

Collective flow harmonics correlations analysis for model data at Nuclotron-NICA energies-1.pdf

15:20 Multiplicity dependent transverse momentum distributions of hadrons of different species in the extended multipomeron exchange model

A new generalization of the Multipomeron exchange model [1-4] for studying the multiparticle production in pp, pA and AA collisions is proposed, taking into account the effect of event-by-event string tension fluctuations [5]. It is shown that the new version of the model correctly reproduces the characteristic thermal behavior of $p_\rm{T}$ spectra in a wide energy range. Simultaneously, the $p_\rm{T}$-multiplicity correlation functions are shown to be satisfactorily described together with the multiplicity-dependent $p_\rm{T}$ spectrum. The new finite mass approach allowed to study contributions to the spectra and correlation functions of various types of identified particles.

The authors acknowledge Saint-Petersburg State University for a research project 103821868.

1. N. Armesto, D.A. Derkach, G.A. Feofilov, p(t)-multiplicity correlations in a multi-Pomeron-exchange model with string collective effects, Phys. Atom. Nucl. 71, 2087–2095 (2008).
2. E. Bodnia, D. Derkach, G. Feofilov, V. Kovalenko, A. Puchkov, Multi-pomeron exchange model for pp and $\mathrm{p}\bar{\mathrm{p}}$ collisions at ultra-high energy, PoS QFTHEP2013 2013, 60 (2013).
3. V. Kovalenko, G. Feofilov, A. Puchkov, F. Valiev, Multipomeron Model with Collective Effects for High-Energy Hadron Collisions, Universe 8, 246 (2022).
4. V. Vechernin, E. Andronov, V. Kovalenko, A. Puchkov, Multiplicity Distributions and Modified Combinants in the Multipomeron Model of pp Interaction at High Energies, Universe 10, 56 (2024).
5. A. Bialas, Fluctuations of the string tension and transverse mass distribution, Phys. Lett. B 466, 301–304 (1999).

Speaker: Kovalenko, Vladimir (Saint Petersburg State University)

Baldin2025Kovalenko.pdf

15:40 → 16:00 Coffee break

16:00 → 18:00 Relativistic heavy ion collisions

Convener: Kovalenko, Vladimir (Saint Petersburg State University)

16:00 Analysis of light hadron spectra obtained with MPDRoot for Bi+Bi collisions at $\sqrt{s_{NN}} = 9.2$ GeV

An analysis of reconstructed $p_T$ spectra for light hadrons ($\pi^\pm$, $K^\pm$, $p$, $\bar{p}$) is presented for simulated Bi+Bi collisions at $\sqrt{s_{NN}} = 9.2$ GeV. The spectra are obtained with MPDRoot. The yield rapidity densities and meson yields are got. An improvement of low-$p_T$ energy loss correction is done.

Speaker: Kolomoyets, Natalia (JINR)

KolomoyetsN_BaldinConf_Spectra.pdf

16:30 Ratios of the average transverse energy density for φ , K+, K- and K* mesons in the range √sNN= 39 GeV - 2.76 TeV and hypothesis of a common production source

We investigate the collision energy dependence of the average transverse energy < (dE_t)/(dy)> at midrapidity registered at midrapidity (|y|<0.5) for identified particles (φ , K+, K- and K mesons) produced in central Au+Au and Pb+Pb collisions over a broad energy range from RHIC to LHC (39 GeV –5020 GeV). Resonances like φ and K have different hadronic cross sections, masses and lifetimes and can be used to study the properties and evolution of the hot and dense QGP medium produced in high energy nucleus-nucleus collisions. Of a peculiar interest is the mechanisms of production of these particles, containing one strange quark.
We present in this report our results of calculations of the average transverse energy at midrapidity using the published data on particle density < (dN)/(dy) > and the mean transverse momenta<p_t> for φ, K+, K- and K* mesons formed in very central (0-5%) Au+Au and Pb+Pb collisions. We found that, similar to our previous studies for φ and K mesons and Ω hyperons[1,2], the collision energy dependence for each particle species is well described by a power-law function of the form ~ Q(sNN)n , Our primary discovery is that the power-law exponent – n, is statistically indistinguishable for all studied particles, from light pions to multi-strange Ω-hyperons. This universal behavior leads to an important property: the ratios of the average transverse energy densities of particles produced in very central nucleus-nucleus collisions are practically constant from RHIC to LHC.
We discuss this observed energy independence of ratios of transverse energies within the framework of the multipomeron exchange model [3]. This interpretation is aimed to check the hypothesis of a possible common underlying production mechanism and provides a method to estimate the fundamental efficient quark-gluon string tension parameter (teff) of the model.
The authors acknowledge Saint-Petersburg State University for a research project 103821868.

1) Shaposhnikova, O., Marova, A. & Feofilov, G.," Open and Hidden Strangeness with Kaons and φ-Mesons in Bjorken Energy Density Approach for Central Collisions from SPS to LHC". Phys. Part. Nuclei 55, 1134–1139 (2024). https://doi.org/10.1134/S10637796247008492).
2) Shaposhnikova O., MarovaA., Feofilov G., "Open and hidden strangeness in central A+A collisions: ratios of the average transverse energy density for ϕ mesons and Ω hyperons in the range \sqrt(s_NN) = 39 GeV - 2.76 TeV", submitted 28.04.2025 to Physics of Atomic Nuclei, ISSN: 1063-7788.
3) Kovalenko, V., Feofilov G., Puchkov A., Valiev F., " Multipomeron Model with Collective Effects for High-Energy Hadron Collisions". Universe 2022, 8, 246.

Speaker: Shaposhnikova, Olga

Baldin seminar.pdf

16:50 Identifying the mechanism of light nuclei production

The formation of weakly bound clusters in the hot, dense environment at midrapidity is among the intriguing phenomena observed in heavy-ion collisions.
Three main approaches have been proposed to describe cluster formation:
- Coalescence at kinetic freeze-out.
- Continuous formation via potential interactions between nucleons.
- Deuteron production through hadronic reactions.
We identify experimental observables capable of distinguishing between these production mechanisms and outline the capabilities of the NICA/MPD experiment for advancing future studies on this topic.

Speaker: Dr Kireyeu, Viktar (JINR)

Kireyeu_Baldin_Seminar_2025.pdf

17:10 RECOVERING COLLISION ENERGY CHARACTERISTICS FROM GEOMETRICALLY CONSTRAINED DATA BY MACHINE LEARNING

Application of machine learning has become highly relevant for solving the problems of event reconstruction, particle identification, and impact parameter estimation [1, 2]. The present study focuses on the application of neural networks to predict the energy released in high-energy collisions of two gold nuclei (Au+Au) based on signals obtained from microchannel plate detectors. The initial data consist of events generated by the QGSM event generator at √(s_NN ) = 11.006 GeV per nucleon–nucleon pair.
For each event, the detector measures the particle’s time-of-flight and hit coordinates on the detector surface, enabling reconstruction of the space-time structure and estimation of the released energy. The pseudorapidity of the detectable particles in the tested configuration is limited to the range 3.5 < η < 5.8. Two neural network architectures were implemented and compared: a fully connected network and a fully connected network with an additional convolutional layer. It has been found that the model with a convolutional layer, where all particles contribute to the released energy in the collision but the feature vector fed into the neural network is formed based on charged particles, gives the best result: root mean square error RMSE = 188.2 GeV and relative error less than 9%. The results confirm the potential of machine learning methods for fast and accurate energy reconstruction in nuclear collision experiments, even with strict geometric constraints.
References
[1] Galaktionov, K. A., Roudnev, V. A., Valiev, F. F. Neural Network Approach to Impact Parameter Estimation in High-Energy Collisions Using Microchannel Plate Detector Data. Moscow University Physics Bulletin, 2023, 78(Suppl 1), S52–S58.
[2] Valiev F. F., Vechernin V. V., Feofilov G. A. Estimation of the Accuracy of Determining the Number of Spectator Nucleons from the Energy Measured in a Calorimeter in A+ A Collisions //Bulletin of the Russian Academy of Sciences: Physics. – 2024. – Т. 88. – №. 8. – С. 1312-1318.

Speaker: Gridiaeva, Polina (Saint Petersburg State University)

english_version.pdf

17:30 First Measurements of Φ Meson Production in pp Collisions at $\sqrt{S_{NN}}$ = 510 GeV.

Abstract. The production of strange Φ mesons in strong interactions is a potential signature for the formation of quark-gluon plasma (QGP) in relativistic heavy-ion collisions. Due to the Φ meson’s instability, it is identified through its decay into kaon pairs $(k^{+}k^{-})$. Since 2022, we at JINR have been conducting an intensive search for Φ mesons in heavy-ion and proton-proton collisions at STAR RHIC BNL. Preliminary results have been obtained. We’ve developed analysis programs to calculate the Φ meson’s invariant mass and employ model-dependent background estimations. The data analysis utilizes minimum bias and central trigger events, incorporating information from the Time Projection Chamber (TPC) and Time-of-Flight (TOF) detectors for kaon identification. This presentation will showcase the preliminary spectrum and yields of Φ mesons, as well as secondary $\pi^{\pm}, k^{\pm}$, and p/p̄ particles, measured in proton-proton collisions at $\sqrt{S_{NN}}$ = 510 GeV. These results are presented prior to corrections for detector efficiency and acceptance.

Speaker: Dr Shahaliyev, Ehtiram

16:00 → 18:00 Studies of exotic nuclei in relativistic beams

Convener: Zarubin, Pavel (Joint Institute for Nuclear Research)

16:00 The Structure of Light Nuclei in Strongly Correlated Quark Model

Speaker: Musulmanbekov, Genis (JINR, LIT)

ISHEPP-2025.pptx

16:30 Synthesis of neutron-rich nuclei at the NICA complex.

The paper presents the results of calculations the formation of light neutron-rich nuclei, including 12He, on beams of short-lived nuclei produced at the NICA accelerator complex. The calculations are based on the reaction of double charge exchange in nuclear-nuclear interactions. The possibility of the neutron-rich nuclei formation on the booster-nuclotron accelerators are discussed. The scheme of identification of the formed isotopes, methods of their selection and interpretation is presented.

Speaker: Afanasiev, Sergey (JINR)

He12-Baldin_XXVI.pdf

17:00 Dissociation features of light relativistic nuclei in fragmentation process in nuclear track emulsions

The phenomenon of multiple fragmentation of relativistic nuclei can serve as a source of coherent ensembles of the lightest nuclei and nucleons. In this respect only nuclear track emulsion providing 0.5 µm spatial resolution allow one to follow tracks of all relativistic fragments in forward cone defined by a nucleon Fermi motion [1]. The report will give a brief overview of the experimental results of the relativistic fragmentation of $^{7,9}$Be, $^{10}$B, $^{10,11, 12}$C and $^{16}$O in the Becquerel project in JINR. The questions of simulating nuclear-nuclear interactions in nuclear track emulsions using Geant4 will be considered. The experimental data will be compared with the simulation. Issues of application of Geant4 to planning and preparing experiments using nuclear track emulsions are discussed [2,3].

1. Web site of the BECQUEREL Project// http://becquerel.jinr.ru (2025);
2. P. I. Zarubin Lecture Notes in Physics, Vol. 875, Clusters in Nuclei,
   Volume 3. Springer Int. Publ., 51 (2013) [arXiv:1309.4881].
3. D.A. Artemenkov et. al., Highlights of unstable states in relativistic dissociation of light nuclei in nuclear emulsion. Intrnational Jornal of Moder Physics E (2024), 2441015.

Speaker: Artemenkov, Denis

artemenkov_ISHEPP25.pptx

17:20 Status of the SCAN-3 at the Nuclotron internal targets

A precision three-arm magnetic spectrometer SCAN-3 is being built for detecting charged (pi, K, p) and neutral (n) particles produced at the LHEP Nuclotron internal target in dA collisions. This project is aimed at studies of highly excited nuclear matter. The matter will be studied through observation of its particular decay products, that is, pairs of energetic particles with a wide opening angle, close to 180.

One of the objectives of the SCAN-3 experiment is to study $\eta$-nuclei, i.e. quasi-bound state of the $\eta$-meson and nucleons of the nucleus. The possibility of registering the decay products of $\eta$-nuclei with the required accuracy is considered. Particular attention is paid to one arm of the setup in the form of a magnetic spectrometer, which should ensure the accuracy of energy determination, first of all, $\pi$ no worse than 4-5 MeV. The tracking system of the magnetic arm contains three single-coordinate straw detectors. Each straw detector consists of two sets of drift tubes with a diameter of 6 mm. The results of arm simulation and testing are presented.

Speaker: Dryablov, Dmitry

Dryablov_ISHEPPXXVI.pdf

Dryablov_ISHEPPXXVI.pptx

17:40 Study the fragmentation of $^7$Be nuclei in mixed beam with nuclear track emulsion

Starting with the discovery of the nuclear component of cosmic rays, the nuclear track emulsion method (NTE) makes an opportunity to study the composition of the relativistic fragmentation of nuclei at high-energy accelerators. The promising potential of the relativistic approach to the analysis of ensembles of fragments was manifested in NTE exposed by nuclei at several GeV per nucleon accelerated at the JINR Synchrophasotron and Bevalac (USA) in the 1970s. Since the 2000s of the NTE method is applied in the BECQUEREL experiment at the JINR Nuclotron in respect to the cluster structure of nuclei, including radioactive ones, as well as the search for unstable nuclear-molecular states. Nucleon associations (clusters) are one of the basic phenomena in atomic nuclei structure. Their simplest observable manifestations are the lightest He and H nuclei. Superpositions of the lightest clusters and nucleons form subsequent nuclei (including unstable$^8$Be and B), which act as constituent clusters themselves for more complicated nuclear systems [1-4]. The phenomena of cluster dissociations of light Be and B isotopes are discussed. Charge topology and angular spectra of fragmentation of 1.2 A GeV $^7$Be nuclei in NTE are presented. The dissociation channels $^4$He +$^3$He, 2$^3$He+ n, $^4$He + 2$^1$H are considered in detail. It is established that the events $^6$Be + n amount about to 27% in the channel $^4$He + 2$^1$H. The experimental results are compared with model data of fragmentation of such nuclei in NTE.

References
[1] P. I. Zarubin Lecture Notes in Physics, Vol. 875, Clusters in Nuclei,
Volume 3. Springer Int. Publ., 51 (2013) [arXiv:1309.4881].

[2] N. K. Kornegrutsa et. al., Clustering features of the 7Be nucleus in relativistic fragmentation, Few-Body Systems, Volume 55, 1021 – 1023 (2014).

[3] P. I. Zarubin et. al., Prospects of Searches for Unstable States
in Relativistic Fragmentation of Nuclei, Physics of Atomic Nuclei, 2022, Vol. 85, No. 6, pp. 528–539.

[4] D.A. Artemenkov et. al., Highlights of unstable states in relativistic dissociation of light nuclei in nuclear emulsion. Intrnational Jornal of Moder Physics E (2024), 2441015.

Speaker: Kornegrutsa, Nadezhda

kornegrutsa_ISHEPP2025.pptx

Saturday 20 September

09:00 → 10:20 Plenary

Convener: Dr Bondarenko, Serge (BLTP JINR)

09:00 Nearly forgotten results in development of physical cosmology

NICA is a tool to investigate the early Universe in laboratory. It would be reasonable to recall some critical issues in physical cosmology development. GR was created by A. Einstein in 1915. In 1917 Einstein proposed the first (static) cosmological model. Soon after the A. Eddington proved that the model is unstable therefore it can not be realizable in nature. In 1922 and 1924 A. A. Friedman found non-stationary solutions for cosmological equations written in the framework of GR. In 1927 G. Lemaitre obtained very similar results and, in addition, he derived the Hubble law (E. Hubble obtained this law from observations). Unfortunately, G. Lemaitre published his paper in not very popular Belgium journal. In 1931 Lemaitre proposed the first version of hot Universe model (he called it hypothesis of the primeval atom). In his book «The Primeval Atom – An Essay on Cosmogony» Lemaitre predicted even a background radiation as a signature of his model. At the end of 1940s G. Gamow and his student proposed his hot universe model where he explained primordial nucleosythesis of helium at the intial stage of the Universe evolution. One of the properties of Lemaitre – Gamow model was a prediction of CMB radiation with a temperature around a few K. I would like to recall that the discovery of CMB radiation was done by T. Shmaonov in 1957 (several years before Penzias and Wilson). In 1965, 1970 E. B. Gliner proposed vacuum like equation of matter which could correspond to exponential explosion of the Universe which was later called inflation. For decades, A. A. Friedmann’s cosmologocal non-stationary models were treated as purely mathematical results without cosmological and astronomical applications. On September 16, 1925 passed away untimely and it would be reasonable to remind today his great contribution in physical cosmology. “Similarly to Copernicus who forced the Earth to move, Friedmann forced the Universe to expand”.

Speaker: Zakharov, Alexander (BLTP JINR, ITEP)

Baldin_20_09_2025b.pdf

Baldin_20_09_2025b.ppt

09:40 Polarization and gravity in hadronic and heavy-ion collisions

The largest ever acceleration and vorticity in heavy-ion collisions corresponds, due to equivalence principle, to extremely strong gravity.
It may be observed due to various polarization effects. Also, the coupling of quarks and gluons to gravity and inertia is controlled by matrix elements of energy-momentum tensors, which may be extracted from polarization effects in hadronic reactions. The special role of MPD and SPD physics in these investigations is discussed.

Speaker: Teryaev, Oleg (JINR)

teryaev2009.pdf

10:20 → 10:40 Coffee break

10:40 → 12:00 Plenary

Convener: Teryaev, Oleg (JINR)

10:40 Highlights of Unstable States in Relativistic Dissociation of Light Nuclei

The 8Be and 9B nuclei and a number of excitations of light isotopes near the binding thresholds constitute a whole class of unusually long-lived states at the lower limit of nuclear density and temperature. In the con-cepts of molecular-like or α-condensate structures, they are represented as associations of the lightest nuclei and nucleons separated in space. Identification of the known unstable states allows studying their dynamics and searching for analogs decaying into them. The report summarizes the key results on unstable states in rel-ativistic dissociation of the isotopes 9,7Ве, 10B, 12,11,10C, 14N and 16O in a nuclear emulsion. Determination of invariant masses of α-particle ensembles from fragment emission angles in the approximation of conser-vation of momentum per nucleon of the parent nucleus allows identification of decays of 8Be(0+), 8Be(2+), 9Be(1.7), 9B, 6Be, 12C(0+2), 12C(3-) and 7Be(7.2) [recently in 1,2 and references therein]. Their identification indicates that the duration and cross-section of the fragment interaction are sufficient for low-energy reac-tions of nuclear astrophysics. Progress in intelligent microscopy and image recognition allows, based on the record spatial resolution and sensitivity of the nuclear emulsion method, to impart new quality and scope to these studies.
1. D.A. Artemenkov et al., IJMP E 24410155 (2024) https://doi.org/10.1142/S0218301324410155; arXiv: 2409.14814.
2. A.A. Zaitsev, P.I. Zarubin “On formation of the 12C(0+2) and 12C(3-) states in relativistic dissociation of light nuclei”to be published in Phys. At. Nucl.; arXiv:2411.18394.

Speaker: Zarubin, Pavel (Joint Institute for Nuclear Research)

ishepp-2025_Zarubin_200925_1.pdf

ishepp-2025_Zarubin_200925_1.pptx

11:20 Jets and quarks at the NICA collider

The report presents proposals for studying the interactions of relativistic nuclei in the space of four-dimensional velocities involving quarks and the formation of hadron jets. It is shown that in the energy range of the NICA collider, fractions of neighboring quarks can participate in the interaction of nuclei. In addition, the behavior of four-dimensional hadron jets is similar to that of hadrons. It appears that the hadronization of quark systems in a jet is determined by the dynamics of interaction with the QCD vacuum, which provides hope for studying the properties of this vacuum.

Speaker: Malakhov, Aleksandr (JINR)

Jets and Quarks.pptx

11:50 Closing

Speaker: Dr Bondarenko, Serge (BLTP JINR)

Closing.pdf