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The XXVth 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 18 to 23, 2023 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 of special importance is just this series of the International Seminars on High-Energy Physics Problems started in 1969 with support of M.A. Markov (1908-1994). They have been given an inofficial, somewhat witty, name "Baldin autumn".
Cosmic ray research at the Physical Institute of the USSR Academy of Sciences motivated the construction of the Synchrophasotron. For this purpose, the Electrophysical Laboratory of the USSR Academy of Sciences was founded in 1953, which became part of JINR in 1956. The most important milestones in the development of the Synchrophasotron itself and experiments on it are presented. Lessons and results that remain relevant to this day are noted. Leaders and key participants are mentioned.
The report presents the history of the construction of the Nuclotron and the results of experiments conducted on it.
Recent results, present status and futures perspectives in neutrino physics will be presented. In the study of neutrino oscillations an emphasis will be put on a search for CP violation and determination of the neutrino mass ordering. The results obtained in current long baseline accelerator experiments T2K and NOvA will be discussed. The brief overview and status of the next generation accelerator based experiments Hyper-Kamiokande (Japan) and DUNE (USA) will be given. New results obtained in the direct measurement of neutrino mass and the progress in a search for neutrinoless double beta decay will be overviewed. A part of the talk will be focused on searches for sterile neutrinos with an artificial neutrino source and in short baseline reactor and accelerator experiments. Finally neutrino parameters obtained in cosmology will be discussed.
The report presents the results of the development of the approach to the study of relativistic nuclear interactions in the four-velocitiy space using the similarity principle.
The essence of the modification of the self-similar approach consists in the inclusion of quark-gluon dynamics in the generation of hadrons in the nuclear-nuclear interactions in the central rapidity region. Inclusive spectra of pions and kaons produced in p+p and nuclear-nuclear collisions were studied as functions of their transverse momentum pT in the central rapidity region, calculated within the framework of a modified approach based on the assumption of similarity of inclusive hadron spectra. A satisfactory description of the NA61/SHINE data for the ratios of the K+/π+ and K−/π− yields as functions of √s in p+p and Be+Be collisions is also presented. The results of calculations of the yield ratios of antiparticles to the yields of particles (anti-p/p, anti-d/d, anti-3He/3He) in proton-proton and nuclear-nuclear interactions using the similarity parameter in the central rapidity region are presented and compared with world experimental data.
In 1963 first quasars were discovered which are supermassive black holes. The Kerr solution is a key component for models of active galactic nuclei (AGNs). In 1968 first pulsars were discovered and their model as rotating neutron stars (NSs) had been proposed. NSs were observed in different spectral band of electromagnetic radiation. In addition, a neutrino signal had been found for SN1987A. Therefore, multi-messenger astronomy demonstrated its efficiency for decades even before observations of the first gravitational radiation sources. Among other gravitational wave events LIGO—Virgo collaborations detected binary neutron star merging in the GW170817 event which was observed also transient in different bands of electromagnetic radiation. We discuss opportunities to test fundamental gravity predictions with observations of black holes and neutron stars.
The measurement of exclusive $e^+e^-$ to hadrons processes
is a significant part of the physics program of the CMD-3 experiment,
aimed to improve the calculation of the hadronic contribution to the
muon $g−2$ and to study the intermediate dynamics of the processes. We
present the most recent results obtained by using the data set of
about 700 pb^-1 collected by the CMD-3 detector at the VEPP-2000
e^+e^- collider at a center-of-mass energy range 0.32 - 2.007 GeV.
In addition to $\Lambda$ hyperon, new data on $\Sigma$ hyperons production are compared to different Monte-Carlo models and contribute to the understanding of hadron production mechanisms.
The first measurements of the transverse momentum ($p_{\rm{T}}$) spectra of $\Sigma^{0}$ and $\bar{\Sigma}^{0}$ hyperons in pp collisions at $\sqrt{s} = 7$ TeV at the LHC are presented. The $\Sigma^{0}$($\bar{\Sigma}^{0}$) is reconstructed via its electromagnetic decay channel $\Lambda(\bar{\Lambda}) + \gamma$, while the $\Lambda$($\bar{\Lambda}$) baryon is detected via its decay into $p + \pi^{-}$ ($\bar{p}$ + $\pi^{+}$). The low-energy photon is measured via conversion into $e^{+}e^{-}$ pairs in the detector material and in PHOS calorimeter by exploiting the unique capability of the ALICE detector.
The complementary results on the first detection of $\Sigma^{+}$ and $\bar{\Sigma}^-$ hyperon at the LHC with ALICE are shown in pp collisions at $\sqrt{s} = 13$ TeV. The $\Sigma^{+}$($\bar{\Sigma}^-$) is reconstructed via its weak decay into p$(\overline{\rm{p}}) + \pi^0$ with the challenging detection of low-energy photons from $\pi^0$ decay.
Also, the first reconstruction and $p_{\rm{T}}$ spectra of the production of $\bar{\Sigma^{\pm}} \to \bar{\rm{n}} + \pi^{\pm}$ in pp and p-Pb collisions are presented. Antineutron is identified and reconstructed with PHOS by unique signature of the annihilation process.
V. Riabov for the MPD Collaboration
The Multi-Purpose Detector (MPD) is a heavy-ion collider experiments at Nuclotron-based Ion Collider fAcility (NICA), which is designed to study heavy-ion collisions in the energy range sqrt{s_NN}=4-11 GeV. Physics objectives of the MPD experiment are to search for new phenomena in the baryon-rich region of the QCD phase diagram, where a phase transition of the first order and existence of the critical end point are predicted. The competitive advantages of the MPD experiment at NICA are the high event rate, possibility of the system size scan, uniform acceptance across different collision systems and energies. Commissioning of the MPD detector and the first data taking are expected to take place in 2025. This report reviews current status of the MPD detector and its physics program, with emphasis on the physics measurements feasible with the first beams.
There is general argumentation establishing bulk/boundary duality in presence of gravity which looks especially simple in the limit of vanishing Newtonian constant. We confront general statements with a particular form of duality between st statistical and geometric approaches developed in Dubna. Applications to physics of heavy-ion collisions are discussed.
The STAR experiment at Brookhaven National Laboratory was built to study the behavior of strongly interacting matter at high collision energy. One of the primary goals for STAR’s experimental program at the Relativistic Heavy-Ion Collider (RHIC) is the investigation of Quantum chromodynamics (QCD) phase properties. These include the search for the location of QCD critical point and the predicted first order phase transition between Quark Gluon Plasma (QGP) and hadron gas. To make a detailed scan on the phase diagram, RHIC has performed two phases of the Beam Energy Scan program colliding Au nuclei at various nucleon-nucleon center of mass energies over the range 62.4 GeV - 7.7 GeV in BES-I and 19.6 - 3 GeV in BES-II. This report will summarize results obtained from BES-I and BES-II energies.
Relativistic heavy-ion collisions provide a unique opportunity to
study the expansion dynamics and the transport properties of the produced
strongly interacting matter. The presentation will review the recent results of anisotropic
flow measurements for collision energies from √sNN = 5.2 TeV to 2 GeV
The generalized parton distribution functions (GPDs) of spin-3/2 particles are given 【1】. Sum rules of those GPDs and structure functions of the systems are obtained. As a typical example, we numerically calculate the electromagnetic and gravitational form factors of the spin-3/2 baryon (like \Delta or \Omega) by using a quark-diquark approach【2-4】. Lattice calculation results are considered to constrain our model parameters. Our study gives a reasonable description for the electromagnetic and mechanical properties of the spin-3/2 particle.
[1] Dongyan Fu, Baodong Sun, and Yubing Dong, Phys. Rev. D106 (2022), 116012, arXiv:2209.12161.
[2] Dongyan Fu, Baodong Sun, and Yubing Dong, Phys. Rev. D105 (2022), 096002, arXiv:2201.08059.
[3] Dongyan Fu, Baodong Sun, and Yubing Dong, Phys. Rev. D107 (2023), 116021, arXiv:2305.02680.
[4] Dongyan Fu, Jiaqin Wang and Yubing Dong, “Form factors of Ω− in a covariant quark-diquark approach”, arXiv:2306.04869.
Short-Range Correlations (SRC) are short-lived fluctuations of strongly interacting highly compact pairs of nucleons. The distance between such nucleons is comparable to their radii and the relative momenta are larger than the fermi sea level. The ongoing world-wide efforts on SRC studies are based mostly on electron scattering experiments, which have shown far-reaching impacts of SRCs on many-body systems, the nucleon-nucleon interactions, and nuclear substructure. The Nuclotron several GeV carbon-12 beam and the BM@N setup allowed for so-called inverse kinematics measurements, where the nuclear fragment(s) are detected after a quasi-elastic knockout reaction. The first SRC experiment at BM@N in 2018 has shown that detection of an intact final state 11B leads to suppression of initial- and final-state interactions in quasi-elastic knockout reaction. Also, 23 events of SRC-breakup showed agreement with electron beam experiments. The analysis of the second measurement of SRC at BM@N in 2022 with an improved setup is currently ongoing. We discuss the preliminary results of the 2022 data analysis and plans for the SRC program at JINR.
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. 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. 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 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).
This simple formalism is used for analysing the resent data on process e+e- -> 𝛬𝑐+𝛬𝑐- obtained recently by the BESIII detector at the BEPCII collider.
The Carpet-2 collaboration reports on the observation and analysis of an event with a low muon content coincident with the gamma-ray burst GRB 221009A and the transient Swift J1913.1+1946. This bright transient was observed by numerous instruments in the optical, X-ray and gamma-ray energy ranges. The redshift of this GRB is z=0.1505 (measured from afterglow observations).
The Carpet-2 array detected an extensive air shower at 14:32:35 UT (1338 s after the SWIFT trigger and 4536 s after the GBM trigger) with the reconstructed arrival direction (RA=289.51°, Dec=18.44°) , which is 1.78° from the direction towards GRB 221009A, well within the angular resolution of Carpet-2 (\approx 4.7°). This event produced zero hits in the 175 m^{2} muon detector of the Carpet-2 array. The reconstructed energy of the primary particle is in the range of 200-250 TeV. We estimate of the probability of the type of particle (photon or proton), its energy and detection efficiency.
Neutron stars have the density of the of the nuclear one, so the methods from the nuclear and particles physics can be used to describe them. However at high densities reached inside neutron stars an additional sensitivity to the certain properties of the baryonic interaction can appear.Therefore studying of neutron stars may be of great importance for understanding the properties of baryonic interactions. At the same time, progress in nuclear physics may be important for the development of neutron stars physics. In the present work we focus on studying of the ΛN interaction.
We consider the neutron stars consisting of nucleons, leptons and Λ-hyperons. The matter of neutron star is modeled based on the Skyrme interaction. Such characteristics as masses, radii and tidal deformabilities of neutron stars are calculated.
We study the influence of the properties of the hyperon-nucleon interaction on characteristics of neutron stars, in particular the difference in description of many-body effects with three-body (ΛNN ) forces and ΛN forces dependent on the nucleon density to the power of γ. We also study the dependence of neutron star characteristics on the value of γ. Using the restrictions on tidal deformability coefficient obtained from neutron stars merger GW170817 we choose some combinations of Skyrme parameterizations, which are more suitable fo describing neutron stars. Finally we consider the charge symmetry breaking effect in neutron stars.
This work was supported by the Theoretical Physics and Mathematics Advancement Foundation “BASIS”.
We investigate the finite-temperature structure of ghost and gluon propagators within an approach based on the rainbow truncated Dyson-Schwinger equations in the Landau gauge. The method early used for modeling quark, ghost and gluon propagators in vacuum is extended to finite temperatures. In Euclidean space, within the Matsubara imaginary-time formalism, it is necessary to distinguish between the transversal and longitudinal, with respect to the heat bath, gluon dressing functions for which the Dyson-Schwinger equation splits into the corresponding system of coupled equations. This system is considered within the rainbow approximation generalized to finite temperatures and solved numerically. The solutions to the ghost and gluon propagators are obtained as functions of temperature $T$, Matsubara frequency $\Omega_n$ and three-momentum squared ${\bf k}^2$. The effective parameters of the approach are taken from our previous fit of the corresponding Dyson-Schwinger solution to the lattice QCD data at zero temperature. In solving the coupled system of the Dyson-Schwinger equations at finite temperatures, the model parameters are treated as constants independent of temperature. It is found that for zero Matsubara frequency, the dependence of the ghost and gluon dressing functions on ${\bf k}^2$ are not sensitive to the temperature $T$, while at ${\bf k}^2=0$ their dependence on $T$ is quite strong. The dependence on the Matsubara frequency $\Omega_n$ is investigated as well. The performed numerical analysis of the solution to the Dyson-Schwinger equations shows that at a certain value of the temperature $T_0\sim 150$ MeV the iteration procedure no longer converges. In the vicinity of $T_0$, the longitudinal gluon propagator increases quite fastly, whereas the transversal propagator does not exhibit any irregularity. This is in qualitative agreement with the results obtained within the QCD lattice calculations in this temperature interval.
Some highlights on studies of strangeness and charm in heavy ion collisions by ALICE at LHC
Grigory Feofilov, Saint-Petersburg State University, RF,
(on behalf of the ALICE Collaboration)
The formation of a strongly interacting medium of deconfined quarks and gluons, known as the quark-gluon plasma (QGP), that occurs in the ultrarelativistic nuclear collisions at the LHC, can
be characterized by several observables. They include, in particular, the enhanced abundances (in heavy-ion collisions relative to that in pp) of rare, strange, and charm hadrons, the presence of
azimuthal flows of identified particles, a strong nuclear suppression of high-pT charged hadrons, peculiar behavior of baryon-to-meson yield ratios, etc. However, recently, some of these QGP signs were found in small systems like pp and p—Pb collisions. These systems were usually thought to have cold nuclear matter effects, not the QGP ones. Therefore, it is interesting to compare the multiparticle production in heavy-ion and small collision systems by using such probes as strange and charm hadrons. Both strange and heavy-flavor quarks are considered to be produced from the QCD vacuum at some early stage of nuclear collision and they interact strongly with the constituents of the QGP. Thus, the study of strangeness and charm production in the case of small and large collision systems could bring valuable information on the hadronization mechanisms. Results obtained in pp, p—Pb, and Pb—Pb collisions as a function of charged-particle multiplicity allow a detailed characterization of the system created in these collision systems. We will show in this report and discuss in some phenomenological models several recent experimental results by the ALICE collaboration got in RUN 1 and RUN 2 in pp, p-Pb and Pb-Pb
collisions at the LHC. This includes the studies of QGP medium induced effects on strange and charm particles yields and on shape of jets, on the azimuthal flows of identified particles, and some
other effects.
In the last part of the talk, we will present challenges by the current new physics programme of measurements in the LHC Run 3 that were successfully met by the recently upgraded ALICE
nstallation. New experimental perspectives of beauty and multi-charm hadrons studies are planned in Run 4 with the new version of the Inner Tracking System (ITS 3) to be installed in 2026-2028.
Finally, new, full Si-pixel sensors ALICE 3 installation that is being designed for RUN 5 (after 2034) will be also presented briefly.
Acknowledgement: Supported by Saint Petersburg State University, project ID: 94031112
This work is devoted to the search for lambda hyperons and short-lived neutral kaons after collision of Xe beams with a CsI target at E = 3.9 AGeV at the BM@N experiment (JINR, Dubna). Simulation, reconstruction and filtering of 100,000 events were carried out. Peaks in the invariant mass distribution corresponding to lambda hyperons and kaons were obtained. Efficiency as a function of rapidity and transverse momentum was derived. All this will enable a better understanding of the transition from baryonic matter to (quark-gluon plasma) QGP in the future.
In the BM@N experiment at the Nuclotron accelerator, the production of $\pi^+$ and $K^+$ mesons in collisions of argon ions with an energy of 3.2 GeV with solid targets of C, Al, Cu, Sn, and Pb was studied. Yields are obtained in kinematic variables in terms of rapidity and transverse momentum. The estimation of the parameters of inverse slopes and multiplicities is performed. The results are compared with microscopic transport models, as well as with data from other experiments.
NICA (Nuclotron-based heavy-Ion Collider fAcility) is a new flagship project at JINR (Dubna, Russia) aimed at the construction of a new accelerator complex for heavy ions and polarized particles [1]. Collisions of relativistic ions with energies up to 11 GeV (center-of-mass) will be studied with the MultiPurpose Detector MPD providing accurate precise tracking and reliable particle identification in high-multiplicity events [2]. Hyperons and hypernuclei are among the most valuable probes in heavy-ion reactions. Production of particles with strangeness is sensitive to the deconfinement phase transition as well as to in-medium hyperon-nucleon potentials [3,4]. Statistical thermal models predict the highest production rates of (hyper)nuclei in the NICA energy range [5], thus the NICA/MPD program offers a unique possibility to investigate the properties of strongly interacting matter in the region of high net-baryon density.
In this talk we’ll overview the prospects of the NICA physics program for the study of hyperons and hypernuclei and discuss the recent results of a detailed feasibility study for the reconstruction of hyperons and hypernuclei with the MPD detector in Bi+Bi collisions. In particular, the expected detector performance for the reconstruction of Lambda-hyperon invariant pT- spectra and 3H\Lambda as well as 4He\Lambda invariant mass distributions in centrality selected Bi+Bi collisions will be discussed.
References
[1] Kekelidze V., Lednicky R., Matveev V. et al. Three stages of the NICA accelerator complex. Eur. Phys. J. A. 2016, 52, 211.
[2] MPD Collaboration. Status and initial physics performance studies of the MPD experiment at NICA. Eur. Phys. J. A 2022, 58, 7.
[3] Johann Rafelski. Discovery of quark-gluon-plasma: strangeness diaries. The European Physical Journal Special Topics 2020, 229, 1-140.
[4] Koch V., Majumder A., Randrup J. Baryon-strangeness correlations: a diagnostic of strongly interacting matter. Phys. Rev. Lett. 2005, 95, 182301.
[5] Steinheimer, J., Gudima, K., Botvina, A., et al. Hypernuclei, dibaryon and antinuclei production in high energy heavy ion collisions: Thermal production vs. Coalescence. Phys. Lett. B. 2012, 714, 85.
Obtaining quality physics results requires high-statistics
data with low background contamination. The task of maximizing
the signal as well as accurate estimation of combinatorial background
is especially important at the start-up of the experiment when the
amount of data is rather limited. The MPD experiment at the NICA collider
will have to deal with such issues in its first run.
In the talk, the task of reconstruction of lambda hyperons with their
weak decay into a proton and a negative pion is considered using
Monte Carlo generated event sample of central Au + Au collisions at
\sqrt{s_{NN}} = 9 GeV. Two approaches for evaluating the combinatorial
beckground in the invariant mass spectra of decay products are presented:
like-sign pair combinations and event mixing.
Background-subtracted and efficiency-corrected hyperon distributions
are presented demonstrating the MPD performance in the future collider
run.
SHiP and the associated SPS Beam Dump Facility is a new general-purpose experiment proposed at the SPS to search for "hidden" particles as predicted by a very large number of recently elaborated models of Hidden Sectors which are capable of accommodating darkmatter, neutrino oscillations, and the origin of the full baryon asymmetry in the Universe. The detector incorporates two complementary apparatuses which are capable of searching for hidden particles through both visible decays and through scattering signatures from recoil of electrons or nuclei. Moreover, the facility is ideally suited to study the interactions of tau neutrinos.
SHiP is declared as an experiment with zero background. The Muon Shield is the key element to achieve this. So on the one hand it have to provide a good background suppression, on the other hand not to be too heavy. The presentation will discuss the issues of Muon Shield optimization, selecting the objective function, considering its constraints from an experimental point of view. Various approaches to global optimization and techniques for accelerating the computational component of the problem will be presented.
During past 30 years in high-energy physic experiments, the detector systems have actively exploited technology based on silicon pixel sensors. Today and in the coming years many of collider’s experiments use pixel detectors as main part for particle tracks identification.
To solve modern tasks in elementary particle physics field (heavy flavor physics, study of charmonium yields at very low transverse momenta, investigations of the space-time evolution of quark-gluon plasma, exotic heavy nuclear states etc.) the precise registration of short-lived particles produced in nucleus-nucleus collisions is needed. In this case it is critical to improve the spatial resolution on the reconstruction of primary and secondary vertices and increase the efficiency of charged particles identification at low transverse momentum. Therefore, leading mega experiments: ALICE, ATLAS, CMS at the Large Hadron Collider, STAR at the Relativistic Heavy Ion Collider (RHIC), MPD, SPD at the NICA collider are using now and will use in the future the silicon pixel sensors as a main element of the vertex detectors in tracking system. Such detectors should have high granularity, high spatial resolution, lower material budget, and higher readout speed.
The present report outlines the vertex detector of new ALICE Inner Tracking System (ITS-3) together with novel technologies based on silicon monolithic active pixel detectors and possible use these technologies for NICA: MPD, SPD, ARIADNA experiments. Also new ideas and developments for mechanic and cooling systems for such pixel detectors are presented.
Acknowledgments: this research has been conducted with financial support from St. Petersburg State University (project No ID: 94031112).
One of the main goals of the beam energy scan physical programs with heavy ions in the range of 2-3.5 GeV is to study the high-density equation of state (EOS) and the search for an onset of a phase transition in dense baryonic matter. Anisotropic flow coefficients are one of the observables that are commonly used in such studies.
Generally, at such energies one can define EOS of the dense matter as a sum of two parts: symetric matter that treats both protons and neutrons in a same way, and symmetry energy that takes into account isospin asymmetry. Properties of the symmetric matter are being studied extensively using charged particles. However, in order to study the properties of the symmetry energy, one needs to measure neutrons.
In this work we present reconstruction performance of the compact highly granular time-of-flight neutron detector (HGN) at the BM@N experiment and discuss first predictions of the anisotropic flow of neutrons using state-of-the-art models of heavy-ion collisions.
Results on determination of the microscopic Hubble constant for pions and nucleons in Au+Au collisions at $\sqrt{s_{NN}} = 7.8$ GeV for a range of times and three impact parameters are presented and discussed. The data are simulated within PHSD model. A typically used method based on the fit of the velocity profile is considered in detail. Also a new method for determination of the Hubble constant is proposed. It consists in the analysis of the statistical distribution of the divergence of the velocity field and getting the Hubble constant as a position of a particular peak of the distribution. A comparison of the methods is done.
Vortical structure of hot-dense matter in heavy ion collisions can be observed through global polarization of emitted particles.
Hyperon's weak decays provides opportunity to measure this phenomenon. Global polarization of $\Lambda$ hyperons was measured by the STAR experiment at RHIC for Au+Au collisions with $\sqrt{s_{NN}}$ = 3-200 GeV and at the LHC for Pb+Pb collisions with $\sqrt{s_{NN}}$ = 2.76 and 5.02 TeV.
Global polarization of multistrange hyperons, such as $\Xi$, can provide new information for hydrodynamic description of the system and its vorticity structure. In this talk, we will report results of $\Xi$ global polarization measurement for Au+Au collisions at $\sqrt{s_{NN}}$ = 19.6 and 27 GeV.
Using first-principle numerical simulations of the lattice SU(3) gauge theory, we calculate the isothermal moment of inertia of the rigidly rotating gluon plasma. We find that the moment of inertia unexpectedly takes a negative value below the "supervortical temperature" $T_s = 1.50(10) T_c$, vanishes at $T = T_s$, and becomes a positive quantity at higher temperatures. The negative moment of inertia indicates a thermodynamic instability of rigid rotation. We derive the condition of thermodynamic stability of the vortical plasma and show how it relates to the scale anomaly and the magnetic gluon condensate.
The coherent inelastic processes of the type $a \rightarrow b$, which
may take place in the interaction of hadrons and $\gamma$ quanta with
nuclei at very high energies ( the nucleus remains the same ), are
theoretically investigated. For taking into account the influence of
matter inside the nucleus, the optical model based on the concept of
refraction index is applied .
Analytical formulas for the effective
cross section $\sigma_{{\rm coh}} (a \rightarrow b )$ are obtained,
taking into account that at ultrarelativistic energies the
main contribution into
$\sigma_{{\rm coh}} (a \rightarrow b )$
is provided by very small transferred momenta in the vicinity of the
minimum longitudinal momentum transferred to the nucleus. It is shown
that the cross section $\sigma_{{\rm coh}} (a \rightarrow b )$ may be expressed through the "forward" amplitudes of inelastic scattering
$f_{a + N \rightarrow b + N}(0)$ and elastic scattering
$f_{a + N \rightarrow a + N}(0)$, $f_{b + N \rightarrow b + N}(0)$
on a separate nucleon, and it depends on the ratios $L_a/R$ and $L_b/R$, where $L_a$,
$L_b$ are the respective mean free paths in the nucleus matter for the
particles $a$, $b$ and $R$ is the nuclear radius. In doing so,
several characteristic cases with different relations of the magnitudes
$L_a, L_b, R$ are considered in detail.
The above formalism
is generalized also for the case of coherent
inelastic multiparticle processes on a nucleus of the type
$ a \rightarrow \{ b_1, b_2, b_3 ....b_i \}$ and for the case
of coherent processes in collisions of two ultrarelativistic nuclei.
Currently, there is no experimental evidences of the violation of the spatial parity (P) conservation in strong interactions. However, the in the QCD theory, the P-breaking term (so-called $\theta$-term) can be included, with tight limits on the $\theta$ parameter value. However, in the medium with high temperature and at large topological fluctuations [1] of QCD fields, expected in collisions of the heavy ions at high energy, the effects of the local violation of P-symmetry can appear. The contribution to the QCD Lagrangian of the topological charge can play role of an effective $\theta$-term [2]. As a consequence, some hadrons would decay in channels that forbidden by the global parity conservation.
In particular, search for decays of a charged a0 meson into charged pion and photon has been proposed [3] as a signature of the local parity breaking in the strong interactions. However the expected electromagnetic cross section of the decay $a_0^\pm \rightarrow \pi^\pm+\gamma$ is rather low making the experimental searches quite challenger [4]. In this work we investigate the hadronc analogue of such process, namely, decay of a charged a0 meson into three charged pions. Both the direct threeparticle decay and a resonance one, with intermediate $\rho^0$ meson ( $a_0^\pm \rightarrow \rho^0 + \pi^\pm \rightarrow \pi^\pm+ \pi^\mp + \pi^\pm$ ) are considered. We study an invariant-mass spectrum of three charged mesons using PYTHIA Monte Carlo generator with enabled required decay channels. To distinguish the peak of mentioned decay from the background the mixed-event substracting, kinematic cuts and Dalitz plots analysis were used. As a result we have estimated minimal number of pp collision events for significant signal of the P-breaking decay.
The study was funded by the Russian Science Foundation grant No. 22-22-00493,
https://rscf.ru/en/project/22-22-00493/
References:
[1] D. Kharzeev, Annals of Physics, 325, 1. 205 – 218 (2010).
[2] A.Andrianov, D.Espriu and X.Planells, Eur. Phys. J. C73 (2013) no.1, 2294
[3] A. Andrianov et al, EPJ Web of Conferences 158, 03012 (2017).
[4] V. Petrov, V. Kovalenko, The possibility of finding the P-symmetry breaking decay of the charged a0 meson, ICPPA-2022, https://indico.particle.mephi.ru/event/275/contributions/3360/
We analyse and give the important details on the Gorishni-Isaev (massless) vacuum integrations. In particular, it has been shown how the delta-function represents either UV-regime or IR-regime. In the case of vacuum integration, we advocate the use of sequential approach to the singular generated functions (distributions).The sequential approach is extremely useful for many practical applications in the effective potential method.
The mass formulas and decay constants of electrically charged and strange pseudoscalar mesons are analyzed within the combined framework of Nambu -- Jona-Lasinio model and the $1/N_c$ expansion up to $\mathcal O(1/N_c^2)$. The light quark masses explicitly violating $SU(3)_L\times SU(3)_R$ chiral symmetry of the strong interactions are taken to be of order $\mathcal O(1/N_c)$. The Fock-Schwinger proper-time method and the Volterra series are used to derive the effective action. A set of sum rules is obtained that relates the phenomenological values of the masses of pseudoscalar mesons to the mass ratios of light quarks. It is shown that combining the new sum rules with the experimental data on the decay width $\eta\to 3\pi$ allows to establish limits for the ratios: $0.47
The associated production of $J/\psi+\gamma$ in proton-proton collisions is discussed theoretically for about 30 years [1], so it is relevant to make predictions for modern colliders energy: NICA ($27$ GeV), RICH ($200$ GeV), LHC ($13$ TeV). The differential cross section predictions were performed analytically and also using the KaTie event generator [2] both in an improved Color Evaporation Model [3] and NRQCD approach [4] at the first time with two different high-energy factorization models: the conventional Collinear Parton Model and the parton Reggeization approach. The parton Reggeization approach is based on the modified Kimber-Martin-Ryskin model for unintegrated parton distribution function [5,6] and Lipatov's effective field theory [7].
[1] Doncheski M. A., Kim C. S. Associated $J/\psi+\gamma$ production as a probe of the polarized gluon distribution // Physical Review D. – 1994. – vol. 49. – n. 9. – pp. 4463.
[2] Hameren A. KaTie: For parton-level event generation with kT-dependent initial states // Computer Physics Communications. – 2018. – vol. 224. – pp. 371-380.
[3] Fritzsch H. Producing heavy quark flavors in hadronic collisions. A test of quantum chromodynamics // Physics Letters B. – 1977. – vol. 67. – n. 2. – p. 217-221.
[4] Bodwin G. T., Braaten E., Lepage G. P. Rigorous QCD analysis of inclusive annihilation and production of heavy quarkonium // Physical Review D. – 1995. – vol. 51. – n. 3. – p. 1125.
[5] M. A. Kimber, A. D. Martin, and M. G. Ryskin Unintegrated parton distributions and prompt photon hadroproduction // Eur. Phys. J. - p. 12, 655 (2000)
[6] M.A. Nefedov, V.A. Saleev High-Energy Factorization for Drell-Yan process in $pp$ and $p{\bar p}$ collisions with new Unintegrated PDFs, Phys. Rev. D 102 (2020), 114018
[7] L. N. Lipatov, Nucl. Phys. B 452, 369 (1995).
A.V. Anufriev
Samara National Research University, Samara, 443086, Russia
V.A. Saleev
Samara National Research University, Samara, 443086, Russia and
Joint Institute for Nuclear Research, Dubna, 141980 Russia
Study of charmonium production at high energy in proton-proton collisions is important test of perturbative QCD, factorization approach and hadronization model in a heavy quark sector. There are many sets of experimental data for $J/\psi$, $\psi(2S)$ and $\chi_{cJ}$ production cross sections [1]. Oppositely, the only results of direct measurements was published by LHCb Collaboration for $\eta_c$ production cross section and transverse momentum spectrum [2]. In the article, we predict $\eta_c$ production cross sections on energies in range from $\sqrt{s}=27$ GeV up to 13 TeV for present and future proton-proton colliders to estimate opportunity of their experimental measurements. We perform our study using different factorization approaches such as Collinear Parton Model (CPM), Transverse Momentum Depended Parton Model (TMD PM) [3], Generalized Parton Model (GMP) and Parton Reggeization Approch (PRA) [4]. $\eta_c$ production cross section is also sensitive to hadronization model of $c\bar c-$pair in the final $\eta_c-$meson. We compare predictions for $\eta_c$ production cross sections using different hadronization models: Color Singlet Model, NRQCD approach and Color Evaporation Model (CEM).
[1] E. Chapon, D. d'Enterria, B. Ducloue, M. G. Echevarria, et al. Prospects for quarkonium studies at the high-luminosity LHC, Prog. Part. Nucl. Phys. 122 (2022), 103906
[2] R. Aaij, C. Abellan Beteta, B. Adeva et al. Measurement of the $\eta_c$(1S) production cross-section in proton-proton collisions via the decay $\eta_c$(1S)$\rightarrow$ $p\bar{p}$. The Eur. Phys. J. C vol. 75, 311 (2015), 579 (2017).
[3] J. Collins Foundations of perturbative QCD. Camb. Monogr. Part. Phys. Nucl. Phys. Cosmol. 32, 1-624 (2011).
[4] V. A. Saleev, M. A. Nefedov and A. V. Shipilova, Prompt $J/\psi$ production in the Regge limit of QCD: From Tevatron to LHC, Phys. Rev. D 85 (2012), 074013
One of the main goals of the Relativistic Heavy-Ion Collider is to investigate the properties of quark-gluon plasma (QGP). Azimuthal anisotropy of hadrons produced in relativistic collisions is considered as a good tool to study QGP’s properties. It can be characterized using Fourier coefficients, where the second coefficient is the elliptic flow ($v_2$). Thus, hadron elliptic flow measurements allow to study the collective behavior of nuclear matter and gain insights into the QGP’s properties.
This talk will present recent measurements of hadron elliptic flow as a function of transverse momentum ($p_T$), centrality, and particle species performed by the PHENIX collaboration. The $v_2$ values for $π^0$ have been measured in Cu+Au collisions at 200 GeV and have been scaled with the participant eccentricity and the cube root of participant-nucleons number. It was found that scaled $v_2$ values are consistent within the uncertainties with those in Au+Au collisions, which demonstrates the independence of elliptic flow from collision system size. At high $p_T > 5$ GeV/c the elliptic flow for $π^0$ has nonzero values. It can be characterized using QGP model predictions assuming the energy loss of partons. The elliptic flow for charged particles has been measured by using three combinations of two-particle correlations in small collision systems (p/d/$^{\text{3}}$He+Au) at 200 GeV. Obtained values are consistent with previous results measured using the event plane method. This fact indicates the robustness of the measurement against the detector's effects. Recently obtained elliptic flow for J/Psi in Au+Au collisions at 200 GeV is consistent with zero, which agrees with $v_2$ for J/Psi at the STAR, but does not agree with the ALICE measurement at 5.02 TeV. It seems that quark coalescence is the dominant mechanism for the development of $v_2$ for J/Psi.
The main purpose of the MPD experiment at NICA collider is to explore the QCD phase diagram of strongly interacting matter produced in nucleus-nucleus collisions at $\sqrt{s_{NN}}=4-11$ GeV. The anisotropic flow of produced particles is one of the important observables sensitive to the transport properties of such matter. The relative elliptic flow fluctuations are of intense interest since they can be used as a probe for the initial conditions using the ratio of cumulants $v_2\{4\}/v_2\{2\}$.
In this work, we study the magnitude of elliptic flow fluctuations characterized by the ratio of cumulants $v_2\{4\}/v_2\{2\}$ using the state-of-the-art models of heavy-ion collisions at $\sqrt{s_{NN}}=5-7$ GeV.
The study of the high-density equation of state (EOS) and the search for a possible phase transition in dense baryonic matter is the main goal of beam energy scan programs with relativistic heavy ions at energies $\sqrt{s_{NN}}$ = 2-5 GeV.
In this work, we discuss the layout of the MPD (NICA) experiment in the fixed target mode and the anticipated performance for differential anisotropic flow measurements of identified hadrons at energies: $\sqrt{s_{NN}}$ = 2.3-3.5 GeV.
In this talk, we explore the potential of azimuthal flow as a tool for investigating color string fusion in proton-proton collisions.
Our approach is based on a detailed simulation of the longitudinal and transverse dynamics of strings leading to their subsequent fusion and decay [1,2]. Using model calculations, we demonstrate that the azimuthal anisotropy of the produced hadrons is sensitive to the presence of the color string fusion. Specifically, flow appears due to a momentum loss that particles exhibit once they pass through the strings [3].
Our findings shed new light on the underlying dynamics of color string fusion in high-energy collisions and may have significant implications for our understanding of the strong interaction.
Supported by Saint Petersburg State University, project ID: 94031112.
More than 360 000 patients were treated at 100 proton and also at 8 heavy-ion cancer therapy facilities worldwide [1]. While beams of protons, $^{4}$He and $^{12}$C nuclei are very effective in killing deep-seated solid tumors, some damage to surrounding healthy tissues is unavoidable and must be reduced. It has been proposed [2,3] to use arrays of thin proton beams, spatially fractionated at the entrance to the patient's body. As shown in a preclinical study [4], this helps to spare normal tissues traversed by protons on their way to the target volume where the beams become wider and finally converge and overlap. The implementation of proton or heavy-ion minibeam radiation therapy (MBRT) is technically challenging in terms of precise shaping of sub-millimeter beams with grid collimators or by magnetic focusing [5]. A detailed modelling of minibeam propagation in tissue-like media is necessary to evaluate the peak-to-valley dose ratio (PVDR) and other parameters linked with the effectiveness of the minibeam therapy.
Using our experience with Geant4 [6] modeling of propagation of therapeutic proton and heavy-ion beams in tissue-like media [7], we simulate minibeams of protons and $^{12}$C in water arranged as rectangular or hexagonal grids with different center-to-center distances and beam widths. Deep-seated target volumes to be irradiated with energetic protons and $^{12}$C are considered because the sparing of a large volume of normal tissues is crucial in this case. The considered minibeam configurations are characterized by dose-volume histograms (DVH) in addition to commonly used PVDR. The results for minibeam configurations of the same geometry for proton and $^{12}$C minibeams are compared for both rectangular and hexagonal grids. Due to the greater lateral divergence, the proton beams provide more uniform irradiation of the target volume compared to $^{12}$C beams. However, further research is needed using radiation biology models to calculate cell survival rates to substantiate firm recommendations for minibeam configurations and choice of protons or $^{12}$C as projectiles.
References
[1] Particle Therapy Co-Operative Group, https://www.ptcog.site/
[2] Y. Prezado, G.R. Fois, Med. Phys. 40, 031712 (2013)
[3] O. Zlobinskaya, S. Girst, C. Greubel et al., Radiat. Environ. Biophys. 52, 123 (2013)
[4] C. Lamirault, V. Doyère, M. Juchaux et al., Sci. Rep. 10, 13511 (2020)
[5] G. Datzmann, M. Sammer, S. Girst et al., Front. Phys. 8, 568206 (2020)
[6] J. Allison, K. Amako, J. Apostolakis et al., Nucl. Inst. Meth. A 835, 186 (2016)
[7] S. Dewey, L. Burigo, I. Pshenichnov et al., Phys. Med. Biol. 62, 5884 (2017)
A synthesis of the research developed in the frame of E&T collaboration, aimed to identify the conditions which maximize the efficiency of an accelerator driven subcritical reactor (ADSR) are presented. Experiments performed in the extended U target “Quinta” irradiated with deuteron and 12C beams with energies 0.5-4 AGeV and simulations realized with the toolkit Geant4 in enriched targets were meant to find on one hand, the optimal beam and energy for ADSR, and on the other hand, the core characteristics that maximize the energy gain G (defined as the ratio of the electrical power produced to the electrical power spent for the plant functioning) and the actinides incineration [1-3].
The information about particle fluence, fission distribution and energy released is obtained from simulations realized with the toolkit GEANT4. The electromagnetic interaction was modeled with standard electromagnetic models. For the inelastic interaction of hadrons intranuclear cascade models were used (Bertini cascade for barions and mesons, binary cascade for ions). In the case of neutrons with energy below 20 MeV the interactions were modeled with the high precision neutron package based on a detailed implementation of the experimental data from ENDF library.
The isotopes evolution was calculated using the spectra registered through simulation to calculate the cross sections for the reactions which contribute to the isotopes accumulation rates and our program written in the frame of toolkit ROOT for solving the system of coupled differential equations through the exponential matrix method. The power produced was obtained from the simulation and for the power spent a method to calculate it by scaling from the data about the accelerator efficiency for a reference particle was used.
Aspects related with the core geometry, the optimal value of the criticality coefficient keff, the material used for the converter, and the enrichment were analyzed. A core with keff 0.985-0.988, Be converter and low enrichment ensure deep actinides burning during a cycle (20-25 % from the initial actinides mass, in comparison with 6-7 % realized in a fast reactor). The optimal proton energy is in the range 1-1.5 GeV, depending on the accelerator type (linear accelerator or cyclotron) with G values 12-14. Ion beams starting with 7Li realize significantly higher G, from 20-25 for 0.25 AGeV 7Li to 35-45 for 16O and 20Ne with energy 0.75-1 AGeV. The influence of the fuel type on the ADSR performance was also, analyzed. Metallic, oxide and nitride fuels with various enrichment distributions were taken into account. The use of nitride fuel is preferable in ADSR because allows to accommodate high power densities.
The most attractive for ADSR is a beam of 7Li with energy 0.25 AGeV. It produces the same net power as 1.5 GeV protons, but necessitates an accelerator 2.6 times shorter, with a reduction of the costs for building and maintenance.
The comparison with the values of the energy gain predicted in fusion power plants (~3 in the case of magnetic plasma confinement [4], ~4 in the case of inertial confinement [5]) demonstrates that ADSR can be a more efficient source of energy.
References
1. Paraipan M., Javadova V. M., Tyutyunnikov S. I., Aspects of target optimization for ADS with light ion beams at energies below 0.5 AGeV, Progr. Nucl. En. 120 (2020) 103221
2. Paraipan M., Javadova V. M., Tyutyunnikov S. I., Influence of Particle Beam and Accelerator Type on ADS Efficiency, Nuclear Science and Engineering (2023) DOI: 10.1080/00295639.2023.2175582
3. Paraipan M., Kryachko I. A., Javadova V. M., Levterova E. A., Tyutyunnikov S. I., Main Results of Neutronical Study about ADS with Ion Beams and Implications on Experiments Planning, Phys. Part. Nucl. Lett. 19 2 (2022) p. 129-144
4. Entler S. et al., Approximation of the economy of fusion energy, Energy 152 (2018) 489-497
5. Meier W.R. et al., Fusion technology aspects of laser inertial fusion energy (LIFE), Fusion Engineering and Design 89 (2014) 2489-2492
Experiments on the study of the neutron spectrum in accelerator systems are of considerable interest. Detailed simulation of an experimental target is a significant phase at preparing for experiments on targets irradiation.
Simulation of a ~21 t depleted uranium target irradiated by 1…10 GeV proton and deuteron particles with the help of FLUKA simulation package was carried out. Neutron spectra and neutron flux in a target volume were obtained. Total number of U-235(n,f), U-238(n,f) reactions occurred in a target were determined. Beam particle power multiplication are calculated.
Heavy charged particles irradiation of the brain leads to the development of progressive cognitive impairment in adults. Partially, the cause of disorders suppression of neurogenesis processes in the dentate gyrus of the hippocampus. But due to the different response of cells, it is difficult to determine the factors that lead to cognitive impairments. To solve this problem, mathematical models of adult neurogenesis are being developed, which are mainly based on data of irradiation C57BL/6J mice of different ages. However, the models do not take into account the entire amount of experimental data, but only a part due to the difficulty of comparing of quantitative data of different experiments.
To summarize the results of irradiation of C57BL/6J mice, we used a comparative analysis of the effects based on the statistical significance of these experiments. During the analysis, were used data on the rates of stages of neurogenesis, the reaction of neurogenesis to irradiation, as well as the results of experiments on the co-labeled of cellular markers. A decrease in the number of cells with an increase in the irradiation dose was chosen as the initial hypothesis. As a result of the analysis, it was possible to identify effects that do not fit into the initial hypothesis of a dose-dependent reaction of cells and, most likely, manifest themselves in narrow intervals of the doses considered. Taking these effects into account in mathematical models of adult neurogenesis can improve the accuracy of predicting the reaction of cells to irradiation.
Radiobiological research in Laboratory of Radiation Biology focusses on addressing both fundamental and applied problems of modern biology and medicine and relies on the availability at JINR of a wide range of radiation sources, including beams of heavy ions of various energies.
In the context of fundamental aspects, our research focusses on understanding of the key physical and biological mechanisms that are responsible for the detrimental effects of radiation at various levels of biological organisation. These studies involve consideration of radiation energy deposition in biological targets, induction of various types of radiation induced damage, the role of biological repair system, the effects of radiomodifying agents etc. One of the milestones achieved in LRB is the solution of so-called RBE (Relative Biological Efficiency) problem. Our scientists clearly demonstrated that the character of RBE dependence on LET (Linear Energy Transfer) of radiation is determined by factors of both physical and biological nature, namely the spectrum of energy deposition in the target volume and the type of critical biological lesions and the ability of cells to repair these lesions. Radiobiological studies with accelerated ions exploiting modern techniques for the detection of molecular and structural DNA damage provided a crucial contribution to the discovery of so-called clustered DNA lesions that are critical events in eukaryotic cells.
The applied aspect of radiobiological studies is associated with the area of radiation tumour therapy and evaluation of radiation risk in space exploration. Despite recent technological improvements in tumour radiotherapy that were achieved through optimisation of dose distribution fields and the use of high RBE particle radiation, the scope for further advances in this area is limited. However, an opportunity for further improvement of radiotherapy remains by exploiting biological factors. One of such approaches is the application of radiosensitising agents aiming to increase the radiosensitivity of tumour cells. In LRB, in vitro and in vivo studies with DNA synthesis inhibitor AraC (cytosine arabinoside) demonstrated an increase in DNA damage, cell death and suppression of model tumour growth after irradiation following application of this agent. Other agents that interfere with cellular DNA repair systems to enhance radiosensitivity are currently under investigation.
In the context of radiation risk assessment in the area of space exploration, the consequences of radiation damage to CNS (central nervous system) from galactic cosmic rays, consisting of high energy protons and high charge and energy ions, are considered as a critical factor. Understanding the initial events and mechanisms of these effects is the main objective of research in this area. To achieve this aim, studies are underway in LRB that include investigation of behavioural reactions of irradiated animals, pathomorphological changes in different parts of the brain, neuroinflammatory processes in microglia that are responsible for radiation-induced neurodegenerative changes in CNS.
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Measurement of the characteristics of quark (q) and gluon (g) jets begins with measuring the q/g-jet fractions in jet sample. To extract the q/g-jet characteristics, two jet samples with significantly different q/g-jet fractions are required. In a real experiment, jet samples differ in kinematics, which leads to the fact that q/g-jet characteristics depend on jet sample. Formulas for kinematic corrections to q/g-jet characteristics are obtained. The technique is illustrated on data from the CMS.
A new 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. The progress of work on the creation of the spectrometer will be discussed.
There are theoretical indications that phase transitions can occur in highly compressed nuclear matter at moderate temperatures. Conventional nuclear physics as well as astrophysical constraints has not yet provided direct evidence for their existence. It is expected that future experiments at the NICA MPD facility will be able to at least partially solve this problem. However, due to the large theoretical uncertainty in the description of multinucleon systems, the interpretation of such experimental data can be very ambiguous. Therefore, the experimental detection of possible transformations in small-nucleon systems is of special importance. In case of their existence, information on the properties of these systems will have scientific value comparable to knowledge of ionization characteristics of atoms for building a microscopic theory of ordinary plasma.
In this paper we discuss the possibility of detecting weakly excited (below the pion birth threshold) deuteron states in d-d → d+d reactions at the colliding beams of the NICA SPD facility at JINR. Since the identification of these processes by the change in momentum or scattering angle of the deuteron is not feasible against the background of the associated elastic scattering processes, the following workaround is discussed. We propose to register protons generated from the decay of 6q states in the kinematic region "almost" forbidden for d-d → p+n+d direct proton knockout processes. Calculations of the contribution to the observed events of very rare deuteron scattering processes on high momentum protons in another colliding deuteron are currently underway. In particular, the problem of fast simulation of the momentum distribution of deuteron nucleons in the whole range of variation of its wave function has already been solved.
A scheme of the dibaryon detection experiment is also proposed, which exploits the effect of flipping the spin of the polarized deuteron in d↑+d ->d↓+d processes.
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. The phenomena of claster dissiciations of ligh Be and B isotops are discussed. Charge topology and angular spectra of fragmentation of 1.2 A GeV $^7$Be nuclei in nuclear track emulsion 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 nuclear track emulsions.
The next topic consisted in the study of unstable states of $^9$Be and $^9$B. The experemental data for this nuclei obtained in relativistic fragmentation of carbon ($^{10}$C) and berillium (from ${10}$B) fragmentation in nuclear track emulsions. The opportunity of searching with nuclear track emulsions for more complex excitations in light nuclei - isobar-analogue states for $^9$Be and $^9$B isotops are discussed [1-3].
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] D. A. Artemenkov et al., $^8$Be and $^9$B nuclei in dissociation of
relativistic $^{10}$C and $^{11}$C nuclei, EPJ Web of Conferences DOI: 10.1051/ conf/201611 0602.
[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.
Following recent results, an overview of fractional analytic QCD beyond the leading order is presented. We demonstrate various representations, details of their derivation, and show the applicability of analytic QCD to the study of the Bjorken sum rule and the decay of the Higgs boson into a bb pair.
We have studied hidden-charm strong decays of the charmonium-like resonant state $Y(4320)$ within the framework of a confined quark model by interpreting the resonance as a four-quark state with molecular-type interpolating current. The strong decay of $Y$ into a vector and a scalar resonance, with the latter decaying, subsequently to a pair of charged pseudoscalar states, has been investigated. We have calculated the partial widths of the strong decays $Y \!\to\! \pi^{+}\pi^{-}J/\Psi$ and $Y \!\to\! K^{+}K^{-} J/\Psi$, and their branching ratio, which is recently determined by the BESIII Collaboration. The estimated proportion of branching and the calculated partial strong decay widths are in reasonable agreement with the most recent experimental results.
Rare $B$-meson decays due to the Flavor Changing Neutral Current (FCNC) $b\to s$ and $b\to d$ quark transitions are quite sensitive to New Physics effects because of the smallness of their decay width. The $b\to s$ transition has been intensively studied both experimentally and theoretically thanks to an enormous sample of $B$-mesons produced at electron-positron and hadron colliders. $B$-meson decays originated by the $b\to d$ transition, being CKM suppressed, get less theoretical attention and experimental data about them are very restricted, in particular, the exclusive $B^+ \to \pi^+ \mu^+ \mu^-$ decay was observed by the LHCb collaboration in 2012 only. This decay is well studied theoretically and predictions are in agreement with experimental data obtained by the same collaboration in 2015. An observation of its electronic counterpart at the LHC is a matter time while additional datasets of $B$-meson will require for its tauonic analogue to be found at the LHC and SuperKEKB. Theoretical predictions for the $B^+ \to \pi^+ \ell^+ \ell^-$ branching fraction, where $\ell = e, \mu, \tau$, are presented based on the effective electroweak Hamiltonian approach and its dependence on the choice of the $B \to \pi$ transition formfactor parametrizations is explicitly analyzed. This decay is also sensitive to long-distance contributions of vector mesons decaying to the $\tau^+ \tau^-$ pair. Their impact on the tauonic invariant-mass distribution and total decay width are evaluated. A possibility of the $B \to \pi \tau^+ \tau^-$ observation at the LHC and SuperKEKB is discussed.
Gell-Mann-Low functions in quantum field theory are usually defined as asymptotic expansions over a small coupling. However their behavior at large coupling is of principal interest, since this behavior sheds light on the general properties of the coupling parameter as a function of a scale variable. We developed an approach, called self-similar approximation theory, allowing for the extrapolation of asymptotic
expansions over a small variable to finite and even infinite values of the variable. The approach is illustrated by several examples demonstrating the convergence of the found strong-coupling exponent to exactly known values. Then the self-similar extrapolation is applied for finding out strong-coupling exponents of perturbative expansions over asymptotically weak coupling for the Gell-Mann-Low functions of
multicomponent scalar field theory, quantum electrodynamics, and quantum chromodynamics.
A.A. Chernyshev
Samara National Research University, Samara, 443086, Russia
V.A. Saleev
Samara National Research University, Samara, 443086, Russia and
Joint Institute for Nuclear Research, Dubna, 141980 Russia
In the article, we study associated production of heavy quarkonia and $D$ mesons in the improved color evaporation model using the high-energy factorization as it is formulated in the parton Reggeization approach. The last one is based on the modified Kimber-Martin-Ryskin-Watt model for unintegrated parton distribution functions and the effective field theory of Reggezied gluons and quarks, suggested by L.N. Lipatov. We predict cross section for associated $J/\psi$ or $\Upsilon$ and $D$ hadroproduction via the single and double parton scattering mechanisms using the set of model parameters that have been obtained early for the description of single and double $J/\psi$ and $\Upsilon$ production at the LHC energies. The numerical calculations are realized using the Monte-Carlo event generator KaTie. The calculation results are compared with the LHC data at the energies $\sqrt{s} = 7 \mbox{ and } 8$ TeV.
A workable basis of quark configurations s^3, s^2p and sp^2 at light front has been constructed to describe the high-Q^2 behavior of transition form factors in the electroproduction of the lightest nucleon resonances. High quality data of the CLAS Collaboration are described in the framework of a model which takes into account mixing of the quark configurations and hadron-molecular states. The model allows for a rough quark core weight in the wave function of the resonance in a comparison with high momentum transfer data on resonance electroproduction.
In the relativistic heavy ion collisions at the beam energy of a few GeV the strongly interacting matter is created at high baryon densities and relatively low temperatures. Azimuthal anisotropy of the produced particles provides a valuable insight into the properties of this form of matter. In this work, we discuss the layout of the upgraded Baryonic Matter at Nuclotron (BM@N) experiment and the anticipated performance for the measurements of the directed and elliptic flow of protons with respect to spectator symmetry plane. We also present the results of the study of scaling properties of anisotropic flow of protons at the beam energies of a several GeV.
This work presents scintillation wall performance during the first run at Nuclotron accelerator with Xe-nuclei collisions and CsI target at a beam kinetic energy of 3.8 AGeV in 2022-2023. The scintillation wall design and its ability to distinguish the charged fragments from nucleus-nucleus collisions will be discussed. The range of measured charges, the operation of the wall and its sensitivity to collision centrality and correlations between the number of fired cells in the wall with observables from other detectors will be shown. Experimental data will be shown in comparison to simulated data.
The study of nuclear multifragmentation in the relativistic energy region provides valuable insights into nuclear clusters and fragmentation characteristics. In this context, the Nuclear Track Emulsion (NTE) detector has been used in the BECQUEREL experiment to analyse the cluster structure of light nuclei, including radioactive ones [1]. NTE detector possess the significant advantages over other detectors. A nuclear emulsion detector with exceptional resolution and high sensitivity used to study the created ensembles H and He as well as a variety of neutrons. The investigation of unstable nuclei, including 8Be → 2α, 9B → 2αp, and the Hoyle states HS → 3α, has been accomplished successfully through the application of relativistic fragmentation [2-3]. The present study focus on the neutron multiplicities observed from 84Kr emulsion interactions at energies below 1 GeV per nucleon in order to comprehend their characteristics. The emulsion plates were horizontally exposed at GSI Germany. The events collected for the present analysis were obtained through the transverse scanning method using the Olympus BX63 microscope. The distance of the neutrons have measured from interaction vertex, and their transverse momentum are calculated from the planer angle observations. The primary analysis reveals that the majority of the neutrons concentrated a region of up to 4 mm and their average transverse momentum of neutrons, including volume factor are 50 MeV/c.
References
[1] P.I. Zarubin, Lect. Notes in Phys. 875, Clusters in Nuclei, Volume 3. Springer Int. Publ.,51 (2013); arXiv:1309.4881.
[2] D.A. Artemenkov et al., Radiation Measurements, 119, 199–203, (2018); arXiv:1812.09096.
[3] A.A.Zaitsev et al., Phys. Lett. B, 820, 136460 (2021); arXiv:2102.09541.
The size and evolution of the matter created in a relativistic heavy-ion collision strongly depend on the collision's initial geometry, defined by centrality. Experimentally the centrality of collisions can be characterized by the measured multiplicities of the produced particles at midrapidity or by the energy measured in the forward rapidity region, which is sensitive to the spectator fragments. We will propose the procedure for centrality determination based on Monte-Carlo sampling of spectator fragments. The validity of the procedure has been checked using the fully reconstructed DCM-QGSM-SMM model events and published data from the NA61/SHINE experiment. Also, we will discuss the prospects of using the proposed procedure for centrality determination in the BM@N and MPD experiments at the NICA facility.
Glauber approach is widely used for describing multiparticle production in the interactions involving hadrons and nuclei in a wide energy range [1-2]. For the more detailed description of nuclear interaction features, this model is increasingly being used at the parton level [3-6], however, usually, the pp-interaction is given insufficient attention.
Before application of the model to nucleus-nucleus collisions, one has to ensure that the major features of the pp interaction are adequately described.
In this regard, in this work the parton-based Monte Carlo model [7] is developed and generalized to proton-nucleus and nucleus-nucleus collisions. It is demonstrated that in pp-collisions the total, elastic, and inelastic cross sections, the slope of the diffraction cone in the energy range from SPS to LHC are satisfactorily described. Using the condition of self-consistency of the model under Lorentz transformations, an explicit form of the dependence of the number of initial partons on the beam energy is obtained, allowing minimization of the number of free parameters.
The model is applied to p-Pb and Pb-Pb collisions at LHC energy. The relation of this approach to Modified Glauber model [8], Multipomeron Model [9], string fusion and percolation model [10] and dipole-based Monte Carlo model [11] is discussed.
This work is supported by Saint Petersburg State University, project ID: 94031112.
In the framework of the model with string fusion we study the correlations between multiplicities in two separated rapidity windows in pp collisions at LHC energies and compare the results with the data obtained by ALICE collaborations at CERN.
The Monte Carlo modelling in the framework of a quark-gluon string model were implies. The string fusion effects were also taken into account by implementing of a lattice (grid) in the impact parameter plane. Correlation coefficient between multiplicities was calculated for three different energies for four values of the width of the observation rapidity windows as a function of the distance between this windows.
The model with string clusters describes the properties of the behaviour of the correlation coefficient: increase with increasing energy, decrease with the increasing rapidity distance between this windows, non-linear dependence on rapidity window's width.
Supported by Saint Petersburg State University, project ID: 94031112.
The talk provides overview of the implementation of the Test Driven Development (TDD) paradigm for verification of the reconstruction engine in MPD offline data analysis framework MPDRoot.
Required changes in the codebase architecture and the environment for diagnostics and data analysis,which are necessary to increase the potential for the future developments for reconstruction engine, are shown.
First results of comparing different reconstruction modules are demonstrated.
Baryonic Matter at the Nuclotron (BM@N) at the NICA complex is a fixed target experiment to study quantum chromodynamic (QCD) phase diagram at large baryon-chemical potential. To extract quality physics information it requires efficient and reliable event reconstruction methods in the conditions of high-multiplicity environment.
Track finding is in the core of event reconstruction methods of any heavy-ion experiment. At BM@N, it is based on a constrained combinatorial search for track candidates, i.e. combinations of detector hits possibly belonging to a track. Possible track candidates are created starting from 3-hit combinations, which are extended from the first detector station and fitted with a Kalman filter procedure to exclude low quality track candidates with high $χ^2$-value.
The algorithm has been implemented as a Vector Finder software toolkit containing track reconstruction procedures and tools to define hit acceptance windows (a priori constraints) for the track search. The method as well as possible constraints for track finding are presented in the talk.
Track reconstruction results for simulated events of heavy-ion interactions are shown demonstrating the performance of the approach proposed.
The lastes run of the BM@N experiment conducted at the beginning of 2023 is officially a physics run, the main purpose of which is to obtain certain scientific results declared in the research program of the experiment.
Due to the increased event multiplicity, in comparison with previous experimental runs, the configuration of the inner tracker was appreciably upgraded: detection planes were added, the quality of the algorithms for simulation and reconstruction of physics events was improved.
The report presents the features of a detailed simulation of the FSD and GEM microstrip coordinate detectors comprised the innner tracking system of the BM@N experiment within the configuration of the lastest eighth run. The development of the detailed ROOT geometry necessary for the simulation of the charged particle passage based on Monte Carlo methods using the Geant4 transport system, as well as features of cluster formation on microstrip readout, are also considered.
The main objective of the proposed experiment is the comprehensive study of the unpolarized and polarized gluon content of the nucleon. In accordance with the possible configuration of the SPD setup, our collaboration manufactured the MiniSPD stand. At present, this stand is used for testing SPD detector prototypes with cosmic muons. Using GEANT4 software and ROOT framework, we have been carried out Monte-Carlo simulation of the three modules of two-sided silicon plates of MiniSPD stand for two cases: with and without taking into account operation of the scintillator triggers. We illustrate the solution of the alignment task which is the important part of any experiment. Our simulation silicon detectors are agreed well with experimental data on cosmic muons.
With the increasing luminosity of modern accelerators in high energy physics, the problem of fast modelling of elementary particle detectors is becoming increasingly important. One approach to fast detector modelling is generative machine learning models, among them Generative adversarial networks (GANs) offer the fastest sampling.
This paper discusses the application of GANs to fast modelling the Time Projection Chamber (TPC) at the Multi-Purpose Detector (MPD) at the NICA accelerator complex. We will examine common challenges that arise during the process and explore potential solutions to address them.
Data-driven techniques are frequently used in high energy physics to get reliable estimate of backgrounds from object misidentification. Here, an approach to the estimation of the background induced by the misidentification of a jet as a photon, in short jet → γ, is presented. It is based on real and fake efficiencies of real/fake photons to pass the tight identification criteria. Selected events are categorized based on the photon isolation. The final number of jet → γ background events in the signal region can be estimated using the control region. The proposed method does not impose any requirements for its application, which is an advantage over other commonly used methods.
The analysis of ALEPH data on femtoscopic correlations of two lambda-hyperons in Z-boson decays yields a very small source radius of 0.11+/-0.03 fm if taking into account only the repulsion due to the Fermi-Dirac quantum statistics. Such a small source radius is counter-intuitive in the string picture of particle production due to a moderate string tension of ~1 GeV/fm. It is shown that the ALEPH data can be desribed with an acceptable source radius of ~0.4 fm if taking into account the repulsive final state interaction between the two lambda-hyperons at distances smaller than a femtometer. Such an information on the two lambda-hyperon potential core is practically inaccessible by other means.
The study of the correlation between the multiplicity of charged particles and the average transverse momentum was carried out in proton-proton and nucleus-nucleus collisions from the SPS energy to the LHC energy [1]. Extending the experimental data from negative correlations at energies √s = 17–40 GeV to lower energies can lead to significant limitations for various theoretical models. Previously, in the SMASH, EPOS, UrQMD, and PHSD models for proton-proton collisions, nontrivial dependences of strongly intense variables on the collision energy were obtained, namely, for Δ[pt, N] [2] and <N>D [pt, N] [3 ]. The analysis also included the study of second and third order cumulants for the transverse momentum. Their energy dependences deviate from the model of independent sources, which is confirmed by experimental data obtained as a result of an Au+Au collision at an energy of 200 MeV [4]. In the SMASH model for proton-proton collisions, both for strongly intense variables and for cumulants, a certain “wave” appears, which can be evidence of a transition from resonance to strings. In this paper, we will study the dependences of strongly intense variables and cumulants on the energy of nucleus-nucleus in collisions, namely Bi+Bi. Two research methods for highly intense variables and cumulants will be proposed: a direct method for studying correlations and a sub-event method. The direct method of research has already been carried out earlier: in this method, research is carried out over the entire interval of pseudorapidity. In the subevent method, it is supposed to analyze strongly intense variables and cumulants of the second and third order in two different intervals in terms of pseudorapidity, as well as their dependence with a change in the distance between these two intervals, which will allow us to estimate the contribution of short-range correlations. A comparison of these two methods will be presented for all four models: SMASH [5], EPOS [6], UrQMD [7], and PHSD [8].
Supported by Saint Petersburg State University, project ID: 94031112.
In strangeness nuclear physics, exotic hypernuclei with a proton or neutron excess are of particular interest now. Such systems relatively poorly explored in experiment can be produced in heavy ion collisions, particularly at NICA complex developed at JINR. Studies of exotic hypernuclei allow to improve the understanding of subtle features of the hyperon-nucleon and hyperon-nucleus interactions. In general, the glue-like role of the Λ-hyperon allows for a chance to stabilize unbound nucleon systems and even get bound hypernuclei with unstable cores. Various aspects of interaction, such as charge symmetry breaking (CSB), may then further affect the stability of these systems.
The structure of light Λ-hypernuclei is treated in the framework of Hartree-Fock approach with Skyrme interaction. This phenomenological approach allows us to analyze the dependence of hypernuclear properties on both nucleon-nucleon and hyperon-nucleon components of the general baryonic interaction. We assess the possibility of the $^9_Λ$C hypernucleus, as well as heavier hypernuclei up to Z = 20, to be bound. To this aim, we verify the accuracy of hyperon binding energy values obtained within the approach. Calculated hyperon binding energies and experimental proton separation energies are then used to examine the stability of a chain of hypernuclei next to the proton drip line. We further show the way to treat charge symmetry breaking ΛN interaction within the Skyrme-Hartree-Fock approach. We calculate the CSB contribution to the hyperon binding energy in proton- and neutron-rich carbon hypernuclei and demonstrate its importance for select exotic hypernuclei.
QED structure and fragmentation functions are systematically derived within the next-to-leading order approximation. DGLAP evolution equations are solved by iterations. Perturbative results are shown for electron parton distribution functions up to O(\alpha^3L^2), where L=\ln(\mu^2/m^e^2) is the large logarithm and \mu is the factorization energy scale. The results are relevant for the present and future experiments at electron-positron colliders.
The complete one-loop electroweak radiative corrections
to the cross section of the process
$e^{+}e^{-} \to e^{-}e^{+}(\gamma) $
are evaluated at low angles with the help of the SANC system.
Numerical results are given center-of-mass energy for the resonant energy of Z boson and 240 GeV in full phase space
with various experimental cuts.
In the relativistic quark model, based on point form of poincare-invariant quantum mechanics, the form-factors of pseudoscalar meson radiative decay $P^{\pm}(q\bar{Q})\rightarrow \ell^{\pm}~\nu_{\ell^{\pm}}\gamma$ are investigated. It's show that taking into account constituent quark structure functions leads to numerical evaluation close to modern experimental data.
Recent results on a study of exclusive processes of $e^+e^-$ annihilation into hadrons with the SND detector at the VEPP-2000 collider at center-of-mass energies below 2 GeV are presented. In particular, we discuss new data on the processes $e^+e^- \to n\bar{n}$, $p\bar{p}$, $\eta\gamma$, $\omega\pi^0$, $\pi^+\pi^-\pi^0$, $\pi^+\pi^-\pi^0\pi^0\eta$.
The review of the transverse momentum dependent (TMD) gluon density and its application to analysis of $pp$ and $AA$ collisions in the wide region of initial energies at mid-rapidity is presented. It is shown that the non-colliniar QCD evolution is sensitive to the TMD gluon distributions at initial scale $\mu_0$. The new TMD gluon density in a proton at $\mu_0$ is suggested using its saturation at low scales observed in DIS at HERA. Corresponding phenomenological parameters important at low $x$ are found from the best description of charged hadron $p_T$-spectra in $pp$ collisions at low hadron transverse momenta $p_T$ in the mid-rapidity at the LHC energies. Other parameters important at moderate and large $x$ are found from the satisfactory description of many data on hard $pp$ processes at LHC energies. The Catani-Ciafaloni-Fiorani-Marchesini (CCFM) evolution equation is applied to extend the initial gluon distribution into the whole kinematical region.
The TMD gluon suggested in [1-4] is used to analyze the pion and kaon inclusive production in $pp$ and $BeBe$ collisions [5,6]. The satisfactory description of NA61/SHINE data on inclusive spectra versus their transverse momenta $p_T$ less than 1 GeV are presented in [5,6]. The data on ratio of cross sections $R_{K/\pi}=\sigma_{K^\pm}/\sigma_{\pi^\pm}$ at the zero rapidity $y$ are also described satisfactorily and predictions for high energies are presented.
Using the suggested TMD gluon distribution we obtain the self-consistent description of soft hadron production in $pp$ collisions at moderate and high energies at mid-rapidity. Extension of proposed initial gluon distribution into the whole kinematical region using the CCFM evolution equation allows us to describe satisfactorily many data on hard $pp$ processes at LHC energies.
REFERENCES
[1] V.A. Bednyakov, A.A. Grinyuk, G.I. Lykasov, M. Poghosyan, Int.J.Mod.Phys., A $\bf{27}$, 125042 (2012).
[2] A.A. Grinyuk, A.V. Lipatov, G.I. Lykasov, N.P. Zotov, Phys.Rev. D $\bf{87}$, 074017 (2013).
[3] A.V. Lipatov, G.I. Lykasov, M.A. Malyshev, Phys.Rev. D $\bf{107}$, 014022 (2023).
[4] A.V. Lipatov, G.I. Lykasov, M.A. Malyshev, Phys.Lett.B $\bf{839}$, 137780 (2023).
[5] G.I. Lykasov, A.I. Malakhov, A.A. Zaitsev, Eur. Phys. J. A $\bf{57}$, 91 (2021).
[6] G.I. Lykasov, A.I. Malakhov, A.A. Zaitsev, Eur. Phys. J. A $\bf{58}$, 112 (2022)
Review of Dubna emulsion experiments performed all the time since 1972 is presented. Different characteristics of 1H, 2H, 4He, 12C, 20Ne, 28Si, 32S, 84Kr, 197Au and 208Pb induced interactions with emulsion nuclei were investigated at ~ (1–200) A GeV/c. The stacks of NIKFI BR-2 4π nuclear detector were irradiated horizontally by nuclear beams at the JINR Synchrophasotron and Nuclotron, the GSI SIS, the BNL AGS and the CERN SPS accelerators. The experimental results were compared with the values calculated by the cascade-evaporation and Fritiof models.
Thanks to its unique spatial resolution, the emulsion detector also enables the fragmentation of relativistic nuclei to be studied in detail. The fragmentation of light relativistic nuclei is also currently being intensively investigated at JINR (not presented here).
In first experiments, the multiplicity and angular spectra of charged secondaries were investigated depending on the impact parameter, which characterizes the degree of centrality of the nuclear collision. The latter was measured in three different ways: according to the size of the total charge of non-interacting fragments of the primary nucleus and according to the numbers of relativistic particles with β>0.7 or slow, target associated fragments.
In order to test the collective behavior of nuclear matter the medium-impact nuclear interactions with heavy 108Ag(80Br) targets were investigated. The transverse-momentum approach, the flow-angle analysis using principal vectors, the azimuthal correlation functions, the method of the azimuthal correlations between the charged secondaries, and the method of the Fourier expansion of the azimuthal angle distributions were applied. The evidence of the directed flow of spectators and the signal of the elliptic flow of participants were observed.
Emission of relativistic particles produced in central interactions with 108Ag(80Br) targets was investigated using scaled factorial moments. An evidence for nonstatistical fluctuations was shown using horizontal factorial moment method in pseudorapidity phase space. The comparative study was done for different beam energies and masses and for different centrality selections. Search for the event-by-event fluctuations was performed. Nonstatistical ring-like structures of s-particles in azimuthal plane of a collision were obtained and their parameters were determined.
An unexpectedly large double-spin correlation $A_{NN}$ was found at large angles in elastic pp scattering ($θ_{c.m.} = 90^◦$ ) at $\sqrt{s_{NN}} = 3$ GeV and 5 GeV in Ref. [1]. These energies correspond to the thresholds for strangeness and charm production in pp collisions, respectively. The observed strong correlations (cross-section ratio of 4 : 1 for parallel and antiparallel spins of colliding protons) are compatible with the assumption of the formation of uudss̄uud anduudcc̄uud octoquark resonances in the s channel that have the quantum numbers of J = L = S = 1, where L is the orbital angular momentum, S is the spin momentum, and J is the total angular momentum of the respective resonance [2]. On the basis of this assumption, the authors of [2] also explained qualitatively an unusual behavior of the color transparency in reactions of the A(p, 2p)B type and oscillations in the differential cross section dσ/dt for elastic pp scattering in the region of manifestation of quark counting rules. However, the last two effects have a different explanation within the nuclear-filtering model [3]. Hard dynamics in elastic pp and pn-scattering may be markedly different. Furthermore, $pn$ channel includes the isoscalar channel in addition to the isovector one. In view of this, it is of importance to study the doubly polarized channel of elastic pn scattering in the same energy range of $\sqrt{s_{NN}}= 3-5$ GeV. This may be done at the SPD in the dd collisions [4]. We studied double spin correlation of the reaction $dd→ pnpn$ with the impulse (double pole) approximation and found that at zero relative momenta of nucleons in both deuterons, when the deuteron S-wave dominates, the transversal and longitudinal $dd$- correlation coincides with the similar double-spin correlation in pp or pn- elastic large angle scattering. Effects of rescatterings and the D-wave contribution are under consideration.
The research is supported under the grant № 411 of the Scientific Program JINR – Republic of Kazakstan.
[1] D. G. Crabb, R. C. Fernow, P. H. Hansen, et al. Phys. Rev. Lett. 41, 1257 (1978).
[2]. S. J. Brodsky and G. de Teramond, Phys. Rev. Lett. 60, 1924 (1988).
[3] J. P. Ralston and B. Pire, Phys. Rev. Lett. 49, 1605 (1982).
[4] V. Abramov et al. Phys. Part. Nucl. 52, 1044 (2021).
Recently the BM@N Collaboration [1] measured the missing momentum and residual nucleus momentum distributions in proton knock-out reactions $^{12}\mbox{C}(p,2pn_s)^{10}\mbox{B}$ and $^{12}\mbox{C}(p,2pp_s)^{10}\mbox{Be}$ in the inverse kinematics with incident $^{12}\mbox{C}$ beam at 48 GeV/c on proton target. Here, "s" stands for an unobserved spectator (or recoil) nucleon. The missing momentum is defined as the momentum of a struck proton in the $^{12}\mbox{C}$ rest frame before knock-out. The observed back-to-back correlation of the missing momentum and the spectator neutron momentum for $p_{\rm miss} \geq 350$ MeV/c indicates that the proton interacted with a short-range $pn$-correlation. We perform the theoretical analysis of this experiment by applying the approach based on the translationally-invariant shell model (TISM) [2] which allows to calculate the spectroscopic amplitude of the state of "$NN$-pair + residual nucleus" in the wave function of the initial nucleus. Our calculations include absorptive initial- and final state interactions and charge exchange processes. In contrast to other approaches, we do not use a phenomenological c.m. momentum distribution of the $NN$-correlation, but calculate it from the TISM. A good overall agreement with the BM@N data is reached.
[1] M. Patsyuk et al., Nature Phys. {\bf 17}, 693 (2021).
[2] Yu. Uzikov and A. Uvarov, Phys. Part. Nucl. {\bf 53}, 426 (2022).
Particles produced in noncentral heavy-ion collisions are mostly twisted (vortex). They are created in electromagnetic and strong interactions. Particles emitted in strong interactions are twisted if initial interacting partons are in twisted states and are untwisted in the opposite case. A vorticity of nuclear matter plays an important role for the production of twisted particles.
The study of resonance production is important in proton-proton, proton-nucleus, and heavy-ion collisions.
Since the lifetimes of short-lived resonances are comparable with the lifetime of the late hadronic phase
produced in heavy-ion collisions, resonance measurable yields are affected by regeneration and rescattering.
These competing effects are investigated by measuring the yield ratios of resonances to that of
the corresponding longer-lived hadron as a function of multiplicity. From these measurements, it is possible
to obtain information on the time interval between the chemical and kinetic freeze-out.
The measurements in pp and p-Pb collisions constitute a reference for nuclear collisions
and provide information for tuning event generators inspired by Quantum Chromodynamics.
In this talk, recent results on short-lived hadronic resonances obtained with ALICE at LHC energies are presented.
These results include system-size and collision-energy evolution of transverse momentum spectra,
yields and the ratios of resonance yields to those of longer-lived particles, and nuclear modification factors.
The results will be compared with model predictions and measurements at lower energies.
One of the main goal of MPD/NICA scientific program is the precise measurement of light hadron spectra. In this report, the MPD performance to measure pt spectra of identified light hadrons at $\sqrt{s_{NN}} = 9.2$ GeV is presented as well as the performance to measure pt-integrated rapidity density dN/dy and full yields of light hadrons.
Recently, a large amount of experimental data has been collected in high energy physics for studying the properties of matter formed in ultrarelativistic heavy-ion collisions. The main interest is to study the phase diagram and localize phase transitions. In this work we measured the thermodynamic properties of the system produced in such collisions. These parameters were obtained from the transverse momentum distributions of final particles based on several theoretical models. Additionally, experimental data were compared with Monte Carlo model simulations. We used the well-known hydrodynamic Blast-Wave approach based on Boltzmann statistics. Results obtained in this comparison are in agreement with published results. Further, we used a new approach based on q-dual statistics, which can provide more information about the system, in particular its chemical potential and measure the difference of the produced system from the equilibrium. We observe that the kinetic freeze-out parameters depend on collision centrality and energy. The temperature in the q-dual statistics deviates from the behavior observed in the model with classical Boltzmann statistics.
We have derived the exact and approximate transverse momentum distributions for the Bose-Einstein, Fermi-Dirac and Maxwell-Boltzmann statistics of particles in the Tsallis statistics with escort probabilities (the Tsallis-3 statistics). The Tsallis-3 statistics is considered by the scientific community to be the most correct. We have found that the classical phenomenological Tsallis distribution in the framework of the Tsallis-3 statistics is questionable as it corresponds to the classical transverse momentum distribution of the Tsallis-3 statistics in the zeroth term approximation for which the entropy of the system is equal to zero for all values of state variables. We have found that the classical and quantum Tsallis-like distributions and the quantum phenomenological Tsallis distributions do not correspond to the transverse momentum distributions of the Tsallis (Tsallis-1, Tsallis-2, Tsallis-3) statistics and $q$-dual statistics. The exact Maxwell-Boltzmann transverse momentum distribution of the Tsallis-3 statistics and the classical phenomenological Tsallis distribution have been compared and applied to describe the experimental spectra of the charged pions produced in the proton-proton collisions at high energies. We have revealed that the numerical results for the parameters of the classical phenomenological Tsallis distribution deviate from the results of the Tsallis-3 statistics for all values of collision energy.
The spectroscopy of charmonium-like mesons with masses above the 2_mD open charm threshold has been full of surprises and remains poorly understood. The currently most compelling theoretical descriptions of the mysterious XYZ mesons attribute them to hybrid structure with a tightly bound diquark or tetraquark core that strongly couples to S-wave DD\bar molecular like structures. The production and decays of XYZ states into light hadron plus charmonum final states proceed via the core component of the meson, while decays to pairs of open-charmed mesons proceed via the DD\bar component. These ideas have been applied with some success to the XYZ states where a detailed calculation finds a cc\bar core component that is only above 5% of the time with the DD\bar component (mostly D0D0\bar) accounting for the rest. In this picture these states are compose of three disparate components: a small charmonium-like core with r_ms < 1 fm, a larger component with r_ms ≈ 1.5 fm and a dominant component with a huge, r_ms ≈ 9 fm spatial extent. The near threshold production experiments in √s_pN ~ 8GeV energy range with pp and pA collisions with √s_pN up to 26 GeV and luminosity up to 10^32cm^-2^-1 planned at NICA may be well suited to test this picture for the X(3872) and other exotic XYZ mesons. Their current experimental status together with hidden charm tetraquark candidates and present simulations what we might expect from A-dependence of XYZ mesons in pp and pA collisions are summarized.
The contributions to the lepton magnetic moment anomaly, $a_L=(g-2)_L/2$, $L=e\ , \mu $ and $\tau$, generated by a specific class of QED diagrams are obtained explicitly up to the tenth order of the electromagnetic coupling constant. Calculations are performed within the Mellin-Barnes integral representation, which is widely used in consideration of multi-loop diagrams. The corresponding analytic expressions are expressed as functions of the lepton mass ratios, $r=m_\ell/m_L$ in the whole range of $r$, $0 < r < \infty$. Our analytic expressions and their asymptotic expansions are compared with the known results available in the literature. Exact analytic expressions for the mass dependent coefficients ${A}_{2,L}^{(10)}(r)$ from the diagrams with insertions of four identical lepton loops are obtained and investigated in detail for the first time. It is shown that approximate expansions can be successfully used for reliable estimates of the corresponding radiative corrections in a large range of $r$ ($0
We report on newest results in kt-factorization for ep-processes. We describe HERA data on longitudinal structure function measurements as well as on associated prompt photon and jet photoproduction. The calculations include first application of the new LLM-2022 transverse momentum dependent gluon distribution developed by the authors. The study includes also the first implementation of parton showers for photoproduction processes in kt-factorization. The data are described well with the simulations. We also present the new version of Monte-Carlo generator PEGASUS, where ep-processes are included.
Using first-principle numerical lattice simulations, we demonstrate that the hot gluon plasma develops strong inhomogeneity with angular rotation. In certain conditions the existence of mixed confinement-deconfinement phase, when the periphery and central regions of rotating system are in the different phases, becomes possible. We study the spatial distribution of the Polyakov loop in the plane orthogonal to the rotational axis and find the conditions when the co-existing of two phases may be possible. We also calculate the local critical temperature for rotating gluon plasma and study its dependence on the angular velocity and radius of the system.
Already for some decades the design and production within Russia of relevant products related to the microelectronics industry critically depends on foreign technologies. In the current scenario it is always more evident the necessity of finding a way to get access to sanctions-free leading-edge electronic components from technological processes below 180 nm to meet the demand specially in high energy physics experiments like those being developed for the NICA facility. This presentation shows a concrete way to achieve this goal based on the ongoing effort for the creation of a research Consortium integrated by JINR, SPbU and several Chinese institutions coordinated by the CCNU for the joint development and production of state-of-the-art Monolithic Active Pixel Sensors (MAPS) for fundamental and applied science experiments, including ASICs-based front-end electronics from the GBTx family to make these technologies freely accessible to China and Russia.
These chips are intended to be the central piece for the joint development and construction of setups for fundamental and applied science at NICA i.e. the MPD Inner Tracking System, and a prototype of a clinical tomograph for the proton Computer Tomography (pCT) for the ARIADNA project.
Wide-gap Resistive Plate Chamber (RPC) have been actively used in high-energy physics experiments since the early 1980s. In the mass production area of TOF MPD the technology for the production of wide-gap RPCs has been developed. The results of testing the prototype on the cosmic radiation stand are presented. The options for using this detector as an alternative to scintillation counters when organizing a trigger system of a test bench TOF MPD are considered.
В работе предложен детектор для измерения светимости в точках сведения пучков на коллайдере NICA. Предложен детектор, основанный на сцинтилляционных счётчиках, который является компактным и может использоваться как автономно, так и в составе базовых детекторов NICA. Проведённые оценки скорости счёта показывают, что для pp и AuAu столкновений число «полезных» отсчётов в минуту превышает 10^4. Предложен алгоритм калибровки детектора на основе скана ван дер Меера. Для параметров NICA рассчитано распределение вершин взаимодействия.
The Spin Physics Detector (SPD) will be installed in the second interaction point of the Nuclotron-based Ion Collider fAcility (NICA) at the Joint Institute for Nuclear Research in Dubna. The main goal is to study the spin structure of the proton and deuteron, and other spin- related phenomena with polarized proton and deuteron beams at a collision energy up to √s = 27 GeV and luminosity up to 1032 cm-2s-1. For the local polarimetry and luminosity control in SPD, several detectors are proposed. This work presents an analysis of the possibilities of using the inclusive reaction, in the end-caps of the electromagnetic calorimeter (ECAL) for local polarimetry purposes. The accuracy of the azimuthal asymmetry of this reaction, as a measure of the beam polarization, is investigated with Monte Carlo simulations in the frame of the SpdRoot code.
CALIBRATION METHODS FOR HALF-SECTORS OF THE MPD/NICA ELECTROMAGNETIC CALORIMETER ON COSMIC RAY MUONS
M.Bhattacharjee(1,3), V.M.Baryshnikov(1),P.A.Bakhtin(5),S.A.Bulychjov(2), B.Dabrowska(1,4), G.E.Fomenko(5), Yu.F.Krechetov(1), V.V. Kulikov(2), M.A. Martemianov(2), M.A. Matsyuk(2), A.Yu.Semenov(1), I.A. Tyapkin(1)
1 Joint Institute for Nuclear Research, Dubna, 141980 Russia
2 National Research Center “Kurchatov Institute”, Moscow, 123182 Russia
3 Gauhati University, Guwahati, Assam 781014, India
4 Plovdiv University Paisii Hilendarski, Plovdiv, Bulgaria
5 National Research Nuclear University MEPhI, Moscow, 115409 Russia
Within the framework of the MPD experiment at NICA [1], a cylindrical electromagnetic calorimeter (ECal) [2-5] with an inner (outer) diameter of 3.45 (4.6) m, a length of 6 m and a weight of 60 tons is under construction. It consists of 38,400 “shashlyk” towers of 64 types, roughly shaped like a truncated pyramid with a base of 4x4 cm2, a height of 40.5 cm and angles between opposite side planes of 0.9 and 1.2 degrees. The ECal implements the so-called projective geometry, when the axes of all towers look at one point of intersection of the heavy-ion collider beams in the center of the cylinder. The ECal is assembled from 50 half-sectors, each containing 768 towers and weighing 1.2 tons. In this report two methods for calibrating the half-sector towers on cosmic muons passing along and across the axes of the towers are discussed. These methods rely on the unique parameters of the readout electronics, which also provide a trigger for the passage of ionizing particles. A peculiarity of the methods is the correction of the tower responses for their spatial orientation. This is implemented by MC simulation in the mpdroot environment. Event selection criteria, parameterization of energy deposition distributions in towers, achievable calibration accuracy, data taking times are analyzed. The two calibration methods are compared both on the simulation data and on the data of the first half-sector measurements. The possibility of applicability of such calibration on a fully assembled ECal is also indicated.
[1] V. Abgaryan et al. (MPD Collaboration) «Status and initial physics performance studies of the MPD experiment at NICA, Eur.Phys.J.A 58 ,7, 140(2022)
[2] A. Yu. Semenov et al. “Electromagnetic Calorimeter for MPD Spectrometer at NICA Collider.” JINST 15 (2020) 05, C05017
[3] V.V. Kulikov et al. “ECAL MPD: geometry and simulation.” JINST 15 (2020) 09, C09017
[4] Y. Li, D. Han, A. Durum et al. “A Shashlyk Electromagnetic calorimeter system for NICA-MPD.” JINST 15 (2020) 11, C11007
[5] Y. Li et al. “Production and quality control of NICA-MPD shashlik electromagnetic calorimeter in Tsinghua University.” JINST 17 (2022) 04, T04005
We test the parametrizations of Fragmentation Functions (FFs) using data on semi-inclusive pion and kaon production in unpolarized pp and heavy-ion collisions at the STAR and NICA kinematics. The calculations are carried out in the next-to-leading order (NLO) of perturbative quantum chromodynamics (pQCD).
We show that at the c.m. energy 200 GeV both LSS-15 and DSEHS-14 FFs for pions and DSEHS-17 FFs for kaons provide the best fits to the STAR data. The comparison for lower energy scales, like at NICA, shows that a purely pQCD approach is inadequate and suggests the necessity to take into account also higher-order effects of initial-state soft-gluon radiation. Nevertheless, these data on the pT spectra of π+ , K+ and also the ratios π-/π+ and K-/K+ seem favour LSS-15 and DSEHS-14 FFs for pions and DSEHS-17 for kaons, similarly as at the energy scale 200 GeV.
The technique of correlation femtoscopy helps one not only to estimate the geometric dimensions and lifetime of the particle emission region in nucleus-nucleus collisions, but also help to answer the question of whether the source has a boost-invariant spatiotemporal structure. This work is aimed to studying the femtoscopic parameters of identical-pion emission region in Au+Au collisions at $\sqrt{s_{NN}} = 3$ GeV in the STAR experiment. The extracted radii ($R_{out}, R_{side}, R_{long}, R^{2}_{out-long}$) and correlation strength ($\lambda$) are presented as a function of collision centrality, pair rapidity and transverse momentum. The obtained femtoscopic parameters are compared with the model predictions.
Two-pion interferometry provides access to the spatial and temporal size, shape and evolution of their sources created in heavy ion collisions and hence offers strong constraints for the theoretical models.
In this work, we will report the measurement of correlation strength ($\lambda$) and femtoscopic radii ($R_{\mathrm{out}}$, $R_{\mathrm{side}}$, $R_{\mathrm{long}}$, $R_{\mathrm{out-long}}$) extracted from the two-pion correlation function in Au+Au collisions at $\sqrt{s_{NN}}$ = 3.2, 3.5, and 3.9 GeV. The dependences of these parameters on pair transverse momentum, pair rapidity, collision centrality, and collision energy will be presented and their physics implications will be discussed.
We present in this talk our estimates of contributions by kaons ($K^{+}+K^{-}$, ($K^{*}(892)^{0}$) and -mesons to the Bjorken energy density relevant to the interaction region formed in the very central (0-5%) A+A collisions. We use the available published data on the identified particle densities at midrapidity and on the mean transverse momenta, obtained in Au+Au, Pb+Pb and Xe+Xe collisions in a broad range of energies (from SPS to the LHC). Particles like K-mesons containing single s-quark and strange-neutral -mesons (a system of $s\bar{s}$ quarks), are of specific interest both from the experimental and theoretical points of view, because they might have different production mechanisms and sensitivity to the properties of the QGP-medium formed in heavy-ion collisions.
Our results show that the behavior of the excitation functions of Bjorken energy density obtained for $\phi$-mesons is different form kaons. We compare also these results with the previously obtained ones for pions and protons and discuss briefly and qualitatively with in the current phenomenological approaches like thermal and coalescence models of particle production.
Femtoscopy is a primary tool for measuring the spatiotemporal characteristics of small and short-lived systems created in particle or nuclear collisions with an accuracy of 1 fm. The possibility of such measurements is due to the effects of quantum statistics and final state interactions which create the momentum correlations of two or more particles at small relative momenta in their center-of-mass system. We report on the calculations of like-sign koan femtoscopic correlations produced in Au+Au at the BES-I region from RHIC using the Ultrarelativistic Quantum Molecular Dynamics Model (UrQMD). We discuss the 3D kaon radii as a function of the transverse momentum of the particles and the centrality of the collision.
Progress in applying the Bethe-Salpeter equation to study relativistic two-particle systems, in particular the deuteron at high energies [1] as well as recent successes in the application of the Bethe-Salpeter-Faddeev formalism for the study of three-nucleon nuclei (helion and triton) (binding energy, state amplitudes and electromagnetic form factors)[2] give a reason to assume that relativistic generalization of the Faddeev-Yakubovsky equation will be just as successful in describing relativistic four-nucleon systems.
The nonrelativistic Faddeev-Yakubovsky equation [3] in integral form for the components of the full four-particle T-matrix is taken as a basis.
This formalism has developed at a fairly good level from a theoretical point of view and was successfully applied, in particular, to the helium-4 nucleus.
In our work, the binding energy of helium-4 is calculated using the relativistic generalization of the Faddeev-Yakubovsky equation with the simplest one-rank separable NN interaction kernel (Yamaguchi).
The results of the calculation are compared with nonrelativistic ones.
[1]S. Bondarenko, V. Burov, A. Molochkov, G. Smirnov, H. Toki, Bethe-Salpeter approach with the separable interac-tion for the deuteron, Prog. Part. Nucl. Phys. 48 (2002) 449–535
[2]S.G. Bondarenko , V.V. Burov, S.A. Yurev. Nucl. Phys. A., 1004 (2020), 122065, S.G. Bondarenko , V.V. Burov, S.A. Yurev. Nucl. Phys. A., 1014 (2021), 122251
[3] O.A. Jacubovsky, Sov.J.Nucl.Phys. 5 (1967) 1312.
Energy levels of three-particle bound systems composed
of a helium nucleus, electron in 1S ground state and Pi^-, K^- mesons
in Rydberg state with principal and orbital momentum quantum
numbers of n\sim l+1\sim 17 are studied in variational approach
in quantum electrodynamics. Vacuum polarization and relativistic
corrections are taken into account.
The hadronic contribution of light-by-light scattering to the hyperfine structure of muonium is calculated using experimental data on the transition form factors of two photons into a hadron. The amplitudes of interaction between a muon and an electron with horizontal and vertical exchanges are constructed. The contributions due to the exchange of pseudoscalar, axial vector, scalar and tensor mesons are considered.
The Standard Model predicts a rapid enhancement of the cross section for scattering of electron antineutrinos on electrons at energies around the $W$ boson production threshold. This enhancement, usually referred to as the Glashow resonance, is currently searched for at the IceCube Neutrino Observatory and its discovery would be a crucial test of the lepton sector of the Standard Model. We show that the CP-conjugate of the process, $\nu_e+e^+\rightarrow W^+$, contributes to the total neutrino-nucleus cross section and can, in principle, be also probed at large-volume neutrino detectors as IceCube, KM3NeT and Baikal-GVD.
As a result of the collision of heavy ions, matter with extremely high acceleration is formed. We show that at such high accelerations, a new quantum phase transition occurs in the medium when its temperature drops below the Unruh temperature. The connection with the behavior of wave modes at the Rindler horizon and the phenomenological implications for hadronization and fast thermalization will be discussed.
Global hyperon polarization and anisotropic transverse flow are important observables for studying the properties of the strongly interacting matter produced in relativistic heavy ion collisions. The former provides information about the initial angular momentum in the non-central collisions and the latter contains the information about the early evolution of the overlap region and the equation of state. Investigation of both effects at NICA energies is an important goal of the MPD experiment. In this work we investigate the global polarization for lambda hyperons and its correlation with the directed flow of the strongly interacting matter created in the Bi+Bi collisions at 9.2 GeV produced with the PHSD event generator.
The absence of really new physics demonstrates that the Nature has put screen to the ''large sledgehammer'' ( LHC) and one can conclude that to put experiment at the forefront in definite sense is similar ''to look for lost keys under lantern because it is more lightly at this place .'' Really, the Nature does not operate with lines, clocks, accelerators and uncountable set of other devices which provide observers with not uniquely defined representations about Nature. There is Nature and our representations about Nature.
If so, it is time to think about a dual scientific paradigm to discover laws of Nature itself which should not to have approximate and temporal character in comparison with those that observers invented in the framework of the current scientific paradigm. But how to realize this possibility?
We put forward an idea that the mathematics (science of numbers) is a base form of internal organization of Nature and consider this as a dual paradigm. In accordance with the universal role of gravity we also pay attention on the seminal work of Einstein and Grossmann published in 1913 ({ Einstein A.}//{ Z. Math. und Phys. }, 1913, {\bf 62}, 225--261. (Mit M. Grossmann)) and Einstein's next year work ({ Einstein A.}//{ Sitzungsber. preuss. Acad. Wiss., }, 1914, {\bf 2}, 1030--1085). On this ground we formulate the first principle of the dual paradigm which is intended to unravel secrets of ordered connection of internal notions and laws according to which the Nature itself is organized.
To find a way that leads from electromagnetism to an internal time of Nature itself in the framework of the dual paradigm, we restore the fundamental notions of electric and magnetic fields, derive the general covariant Maxwell equations for these fields and recognize that the general covariant fundamental notion of the interval is determined
not the Lorentz group but a general covariant bilateral symmetry. With this, we have possibility to give definition of an internal time of Nature itself as well recognize that there are two different internal times. The dual internal time clearly demonstrates that in certain sense the well--known idea of rotating rigid body of classical mechanics is as fundamental as the idea of massive point, i.e., the first concept can be reduced to the second one at the fundamental, field--theoretical, level ( {Ivanhoe B. Pestov}.{\it New Fundamentals for Particle Physics. Emergent Spin and Duality of Time. // In: Horizons in World Physics, Volume 302, Chapter 4, pp. 77--118}. Nova science publishers, Inc, New York, 2020; Preprint JINR E2--2022--57, Dubna, 2022). This explains why nucleus exist in Nature and opens completely new possibilities to explain nature of nuclear matter.
The proposed polarized 3He++ acceleration in RHIC and the future Electron-Ion Collider will require about 2 × 1011 ions in the source pulse. A new technique had been proposed for production of high intensity polarized 3He++ ion beams. It is based on ionization and accumulation of the 3He gas (polarized by metastability-exchange optical pumping and in the 5 T high magnetic field) after upgrade to Extended (EBIS) Electron Beam Ion Source. A novel 3He cryogenic purification and storage technique was developed to provide the required gas purity. An original gas refill and polarized 3He gas injection to the EBIS long drift tubes, (which serves as the storage cell) were developed to ensure polarization preservation. An infrared laser system for optical pumping and polarization measurements in the high 3–5 T field has been developed. The 3He polarization 80–85% (and sufficiently long ∼30 min relaxation time) was obtained in the “open” cell configuration with refilling valve tube inlet and isolation valve closed.The Extended EBIS should also increase un-polarized multiply charged heavy ion production from helium to uranium. A proposal for 3He++ (and multiple charged heavy ions) for NICA collider will be also discussed.
The phenomenon of locking of color quarks Nc=3 in the proton-neutron - in hadrons- and the existence of three quark-lepton generations Ng=3 open the way to expanding the foundations of quantum physics itself. In this report, we will discuss a generalization of the unitarity condition with possible practical applications.
Field-theoretical approach of the vector meson resonance production in reaction
$A+B\Longrightarrow V+X\Longrightarrow 1+2+X$ is applied to the
determination of location of the $V$-meson spin quantization axis.
In this approach amplitude of the reaction $A+B\Longrightarrow 1+2+X$ is
a product of the on shell and off shell amplitudes of
the subreactions $A+B\Longrightarrow V+X$ and $V\to 1+2$ correspondingly.
Off shell behavior of the $V$-meson decay amplitude
ensures separability of the amplitude $A+B\Longrightarrow 1+2+X$
and indicates the need to take into account the decay width of the $V$-meson resonance.
The 3D time-ordered relativistic field-theoretical equations are suggested
for the off shell $V$-meson decay amplitude $V\to 1+2$.
It is shown that the special cases of the considered formulation were used
in numerous high energy experiments in order to study of asymmetries
and alignment of the particles 1 and 2 in
reactions $A+B\Longrightarrow V+X\Longrightarrow 1+2+X$.
Special attention is given to the partial wave decomposition of the
relativistic amplitudes and cross section over the
the orbital moments and spin of the
intermediate $V$-meson and final particles 1 and 2. Equivalence of this
partial wave decomposition and Jacob-Wick decomposition is considered.
The detector for adjusting the convergence of beams at the point of interaction of the MPD (Multi-Purpose Detector) installation at the NICA collider (Nuclotron-based Ion Collider fAcility) is discussed. Simulation of the detector operation for Au+Au collisions at √(S_NN )=11 ГэВ is calculated. It is shown that background events from scattering on residual gas give a negligible contribution to the detector's samples. The calibration procedure for determination absolute luminosity in the MPD interaction zone with the help of this detector is considered.
The MPD NICA experiment, which will study heavy-ion collisions at energies of $\sqrt{S_{NN}}=4-11$ GeV, is currently under construction at JINR, Dubna. To date, several methods have been developed to determine centrality of heavy-ion collisions. One of the approaches is relied on the spatial energy distributions in Forward Hadron Calorimeters (FHCal) modules. The other method is the commonly used approach of collision centrality determination based on track multiplicity from a Time-Projection Chamber (TPC). Both approaches have their own advantages and drawbacks. This work presents the preliminary results of a new centrality determination method development that relies on both observables from FHCal and TPC. The method provides the ability to determine centrality classes from 3D-correlation of observables from FHCal and TPC. This correlation of track multiplicity in TPC and energy distributions in FHCal and subsequent division of events into centrality classes provide better centrality resolution especially for central collisions. In addition, the presented approach provides a basis to relate the energy deposition in the calorimeter to the Glauber model.
We discuss a few approaches in energy calibration of Forward Hadron Calorimeters (FHCal) at MPD with cosmic muons. A few types of muon tracks in FHCal modules were considered. The straightforward method is the selection of horizontal muons that are parallel to the longitudinal axis of calorimeter modules. In this case the energy deposition in each longitudinal sections of FHCal module is about 5 MeV and equals to the energy loss of minimum ionizing particles (MIPs). This approach requires the data acquisition for a few days to collect a statistically reliable data. Therefore, another solution was tested based on muon track reconstruction for various entry angles. In this technique the length of muon track in each longitudinal section of FHCal module was evaluated with the subsequent correction of energy deposition to this length.
This technique faces several problems connected to heterogeneous calorimeter structure which make the use of some muon entry angles unreliable. Calibration results for both approaches will be presented and compared.
The Time Over Threshold (TOT) method using a pulse shaper based on the mathematical function of the raised cosine (FPC) is described. FPC has an important property for this method – the formation of a smooth pulse, with the variability of the smoothing coefficient and response time. At the same time, the shape of the FPC pulse does not depend on the input pulse waveform in a given time range. Thus, on the basis of the FPC, it was possible to create a pulse sine shaper with a given time response, providing an unambiguous dependence of the pulse duration on the input charge, as well as to improve accuracy characteristics due to optimal spectral filtering in the FPC. A pulse sine shaper based on FPC was successfully used in the reading systems of the HADES experiments (GSI, Darmstadt, Germany) and BM&N (JINR, Dubna). The total number of reading channels was more than 5000, the method error is about 0.3%.
The Spin Physics Detector is an experiment at NICA designed to study the spin structure of the proton and deuteron and the other spin-related phenomena using polarized beams. Two endcap detector wheels of scintillator-based Beam-Beam Counters (BBCs) will be installed symmetrically aside from the interaction point and will serve as a tool for beam diagnostics including local polarimetry.
In this talk, we present the materials selection using scintillation tiles with different material combinations of the BBC prototype. The influence of the light collection was studied using matte and covered with Tyvek tiles. Different fibers (Saint Gobain BCF91AS, BCF92S, and Kuraray Y-11), as well as different optical cements (CKTN mark E, OK-72) were used. The prototype was tested with cosmic rays and radioactive source using SensL SiPM readout.
The Geant4 FTF model is one of two hadronic models applied in the Geant4 package [1] for simulations of particle’s and nuclei interactions with matter. It is used in many practical applications. Thus, it is very important to tune the model parameters to reproduce known experimental data. In the last decade, a large amount of experimental data on proton-proton (pp), proton-nucleus (pA) and nucleus-nucleus (AA) interactions have been obtained by the NA61/SHINE Collaboration. As shown by the collaboration, most of Monte Carlo event generators, except the EPOS model, cannot describe the data. Some progress has been made in the Geant4 FTF model.
The FTF (FRITIOF) model assumes that di-quarks are essential components of baryons. Thus, we tune, first of all, a probability of meson production at di-quark fragmentations, and describe proton spectra in proton-proton interactions [2]. K- mesons are mainly produced at quark fragmentation in the interactions. The yield of the mesons is proportional to a probability of strange quark-antiquark pair’s creation at quark-gluon string fragmentation (~ 12%). In order to reproduce the energy dependence of the yield [2], we introduce a dependence of the probability on a string mass, and tune its parameters. The K+ meson yield is determined both by the quark fragmentation and a process of meson emission by the di-quarks. The NA61/SHINE experimental data on the K+ meson production in pp-interactions cannot be fitted tuning parameters due to the data scattering. Thus, we turn to the NA61/SHINE data on Λ-hyperon and K0s meson production in pp-interactions at projectile beam momentum 158 GeV/c [3,4], and tune the parameters. In order to check the tune, we analyzed data on p+C interactions at 31 GeV/c [5]. They are described well changing the probability of strange quark-antiquark pair’s creation a little bit. The analogous change is larger for nucleus-nucleus interactions than for pA interactions. As a result, we describe the NA61/SHINE data on AA-interactions well enough starting at beam momentum of 13 GeV/nucleon up to 150 GeV/nucleon [6,7]. The tuned Geant4 FTF model can be used to provide reference data for NICA experiments.
1. Geant 4 Collaboration (J. Allison et al.) Nucl. Instrum. Meth. A835 (2016) 186.
2. NA61/SHINE Collaboration (A. Aduszkiewicz et al.) Eur. Phys. J. C77 2017) 671. PP
3. NA61/SHINE Collaboration (A. Aduszkiewicz et al.) Eur. Phys. J. C76 2016) 198. Lam.
4. NA61/SHINE Collaboration (A. Aduszkiewicz et al.) Eur. Phys. J. C82 2022) 96. K0s
5. NA61/SHINE Collaboration (N. Abgrall et al.) Eur. Phys. J. C76 2016) 84.
6. NA61/SHINE Collaboration (A. Acharya et al.) Eur. Phys. J. C81 2021) 397 Ar + Sc
7. NA61/SHINE Collaboration (A. Acharya et al.) Eur. Phys. J. C81 2021) 73. Be7 + Be9
This report is dedicated to multiparticle production in lepton and hadron interactions, in particularly, the region of high multiplicity.
Our gluon dominance model allows us to describe multiplicity distributions in these processes. This model includes two stages: partonic and hadronization. It confirms the active role of gluons in multiparticle production. predicts a few collective phenomena in the region of high multiplicity: pionic (Bose-Einstein) condensate formation, excess of soft photon yield, Cherenkov radiation of gluons and others. They have been observing at U-70 accelerator in pp interactions.
We propose to study some of them at the SPD setup.
There are some indications on the existence of two barion states, that are systems with barion
number 2(dibarion) and excitation energy lower than π0 mass. Such state according to barion
number conservation after its production decays into proton and neutron and has a mass MX =
Md + Eexc,where Md and Eexc are deuteron mass and excitation energy.
The simulations of dd collisions is performed in assumption that in final state we have deuteron
and dibarion with mass MX. Eexc is taken here as a fraction 1/4,1/2,3/4 of π0 mass equal to
0.135GeV , what corresponds to MX equal to 1.90935,1.9431,1.97685 in GeV respectively.
Momenta of colliding deuterons were taken equal to 2.6 GeV/c what corresponds to the conditions
of Baldin et al. experiment (Baldin A.M. et al.,Communication of the JINR, Dubna 1979,1-
12397). This study is performed under the conditions that the collider momentum is fixed at the
2.6 GeV/c;the transferred momentum of unbroken deuteron t = -0.5 (GeV/c)2,all the collisions
take place at the center of the detector, and the dibarion has zero decay width.
The analysis shows that the resolution of dibarion mass under these conditions is ≈ 2−3 MeV
and opening the way to propose the study of this process at the commissioning stage of SPD
detector.
The HGN (High Granular Neutron) detector is being developed for the BM@N (Barionic Matter at Nuclotron) experiment on the extracted beam line of the Nuclotron (JINR, Dubna) to measure the azimuthal flows of neutrons with energy range 400 - 4000 MeV produced in heavy-ion collisions at the beam energies 2 – 4 AGeV. This data together with data of azimuthal flows of charged particles, which will be measured separately in the BM@N magnet spectrometer are necessary to study the EoS of isospin-symmetric dense nuclear matter, which is crucial for studying astrophysical phenomena like neutron stars and their mergers.
The HGN detector has a high granular structure with using about 2000 plastic scintillation detectors with a size of 4×4×2.5cm3 arranged in 16 layers of 11×11 detectors placed between 3cm copper absorber plates. The light detection from each scintillation detector is provided with one SiPM with active area 6x6 mm2. Multi-channel TDC board developed on Kintex FPGA chip with 100ps time bin width will be used to perform precise timestamp and amplitude measurement using Time-over-Threshold (ToT) method. Good spatial resolution due to the high granularity together with a time resolution of 100-150ps ensures neutron energy reconstruction with 5-10% relative energy resolution.
The design of the detector as well as results of simulations will be discussed. Measured time resolution of the samples of scintillation detector with different types of scintillators and SiPMs will be presented.
A new high-granular neutron detector is under development for the BM@N experiment, JINR, Dubna, Russia. Its task is to measure the anisotropic collective neutron flow in the energy range of 1-4 AGeV. This measurement is crucial for studying the symmetry energy term in the equation of state of strongly interacting hadronic matter. The detector is designed with a high-granular structure, incorporating approximately 2000 plastic scintillators organized into layers, situated between absorber plates. Detection of light from each scintillation detector is achieved using a single silicon photomultiplier with the data being gathered using a single-threshold multichannel TDC. This report is focused on analytical description of signals from plastic scintillator detectors captured by silicon photomultipliers. This description, based on physical principles, is essential for understanding the Time-over-Threshold (ToT) and amplitude relationship and applying slewing correction techniques to improve the detector's time resolution.
We present some results of analysis of hadron production in $pp$ and $AA$ collisions obtained in the framework of $z$-scaling and discuss a possible signatures of a phase transition in nuclear matter. This approach allows to systematically analyze experimental data on inclusive cross sections over a wide range of the collision energies, multiplicity densities, transverse momenta, and angles of various particles. The concept of the $z$-scaling is based on the principles of self-similarity, locality and fractality reflecting general features of particle interactions. 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 energy and centrality dependence of $K_S^0$-meson spectra measured by the STAR Collaboration at RHIC in $Au+Au$ collisions over a wide range of $\sqrt {s_{NN}} =7.7-200$~GeV was studied in the $z$-scaling approach. The scaling function $\psi(z)$ was constructed and the self-similarity of $K_S^0$-meson production was confirmed. Anomalous behavior of "specific heat" $c_{AuAu}$ and fractal entropy in dependence of collision energy was found. The non-trivial dependence of $c_{AuAu}$ on the collision energy shows that $K_S^0$ meson is much more sensitive to properties of nuclear medium than a non-identified negative hadron A non-trivial dependence of fractal entropy $S_{\delta ,\epsilon}$ on the collision energy with decreasing $p_T$ was found. It reflects the irregularity of the behavior of the specific heat $c_{AuAu}$. The irregularities in the behavior of specific heat parameter $c_{AuAu}$ and fractal entropy $S_{\delta , \epsilon}$ considered as a possible indication of phase transition in nuclear matter are discussed.
Monte Carlo (MС) AuAu events at the energy of √sNN = 200 GeV obtained using A Multi-Phase Transport (AMPT) generator [1, 2], MС fractals and events with randomly distributed particles are analyzed by the SePaC method [3]. The dependence of the portion Prtn of the events under study, determined by the method as fractals, on the parameter PMax was studied. It was found that the hypotheses of independent and dependent division of fractals correspond to different regions of the Prtn(PMax) distribution for the MC of AuAu events. Such a behavior allows us to apply the SePaC method [4,5] with different hypothesis separately [4,5]. It is shown that the distributions of events on the fractal dimension DF are different for these hypotheses. It was found that the events reconstructed by the independent division hypothesis have a group of leading particles in the transverse momentum space, while the remaining ones show the exponential behavior of the pt spectrum. The results of applying criteria describing the statistical characteristics of structures [6] showed that a large fraction of events (86%) reconstructed by the independent division hypothesis have the same fractal structures at different levels.
The results of an analysis of the invariant mass spectra of photon pairs produced in dC, pC
and dCu interactions at momenta of 2.75, 5.5 and 3.83 GeV/c per nucleon respectively, are
presented. Signals in the form of enhanced structures at invariant masses of about 17 and
38 MeV/c2 are observed. The results of testing of the observed signals, including the results
of the Monte Carlo simulation are presented. The test results support the conclusion that
the observed signals are the consequence of detection of the particles with masses of about
17 and 38 MeV/c2 decaying into a pair of photons.
The report describes the new drift cameras developed for the ALPOM-2 experiment, their main characteristics and methods of operation.
The paper also describes the experience of working with ASD-8 chip, modernization of boards containing it, which allows to avoid problems with noise and to abandon obsolete preamplifiers.
A novel method of deuteron spin-flipping by the spin resonance crossing due to the betatron tunes shift is proposed. The resonance is induced by Nuclotron corrective quadrupoles, which allow one to control the resonance detuning and its strength simultaneously. Spin-flipping of deuterons is provided by adiabatic crossing of the induced resonance due to a slow change of the vertical betatron tune. The advantage of this approach is that during induced resonance intersection the energy of the beam remains unchanged and is determined by the selected tune of the vertical betatron oscillations. The polarization profile, which depends on the betatron amplitudes distribution and the resonance crossing rate, is calculated. The feasibility of experimental verification of deuteron spin-flipping in Nuclotron is discussed.
Nucleosynthesis at large magnetic induction relevant for core-collapse supernovae, and neutron star mergers is considered. For respective magnetic fields of a strength up to ten teratesla atomic nuclei exhibit linear magnetic response due to the Zeeman effect. Such nuclear reactivity can be described in terms of magnetic susceptibility [1]. Susceptibility maxima correspond to half-filled shells. The neutron component rises linearly with increasing shell angular momentum, while the contribution of protons grows quadratically due to considerable income from orbital magnetization. For a case j = l + 1/2 the proton contribution makes tens of nuclear magnetons and exceeds significantly the neutron values which give several units. In a case j = l – 1/2 the proton component is almost zero up to g-shell. Respectively, a noticeable increase in the generation of corresponding explosive nucleosynthetic products with antimagic numbers is predicted for nuclei at charge freezing conditions. In the iron group region new seeds are created also for the r-process. In particular, the magnetic enhancement of the volume of 44Ti isotopes is consistent with results from observations and indicates the substantial increase in the abundance of the main titanium isotope (48Ti) in the Galaxy’s chemical composition. Magnetic effects are proved to result in a shift of the r-process path towards smaller mass numbers, and an increase in the volume of low mass nuclides in peaks of the r-process nuclei..
1. V.N. Kondratyev // Universe, 7 (2021) 487
We develop a theoretical description of the production of pions and protons in a new cumulative region of central rapidities and large transverse momenta that can be observed in nuclear collisions by the MPD and SPD detectors of the NICA complex.We suppose that particles in this kinematic region, inaccessible for single nucleon-nucleon interactions, are formed as a result of scattering from the so-called nuclear fluctons, which are considered as clusters of cold quark-gluon matter with a high baryon density.
We calculate particle yields in this new cumulative region due to the interaction of a nucleon of one nucleus with a flucton of another nucleus. To this end, we generalize the microscopic quark approach developed in [1–6] for describing the production of cumulative particles in the fragmentation region of one of the colliding nuclei to the case of particle production in this new region.
We show that there is a change in the ratio of the proton to pion yield in the region of central rapidities and high transverse momenta compared to the cumulative region of nuclear fragmentation. The reason is that, as shown in [4-6], in the case of cumulative pion production, the process of fragmentation of a single flucton quark into a pion dominates, while in the case of cumulative proton production, the mechanism of coherent coalescence (recombination) of three flucton quarks into a proton dominates.
It is also noted that studies of particle production in this new cumulative region are available for experimental study only at relatively low initial energies of colliding nuclei of the NICA collider facility and are not available for experimental study at the RHIC and LHC colliders.
We compare the obtained theoretical results with the results of our preliminary estimates of particle yields in this region based on a more phenomenological approach [7-9].
The work was supported by the Russian Science Foundation grant 23-12-00042.
Characteristics of two forms of the electron-hole (eh) plasma radiation, excited in the graphene under the action of an external time dependent electric field, namely, the quasiclassical radiation of plasma waves and the quantum photon emission in the annihilation channel of interaction of the eh-plasma with a quantized electromagnetic field, are investigated and compared among themselves by analytical and numerical methods. The analysis is based on a consequent kinetic theory where the excitation of the eh-plasma by an external field is described nonperturbatively [1, 2], while the interaction with a quantized field is taken into account in the second order of perturbation theory [3]. It is showed that the peculiarities of two types of radiation (spectrum, radiation patterns) are accessible for experimental verification. The obtained results are compared also with a direct analysis of the photon emission in the graphene, based on an exact solution of a Dirac-like equation [4], and also with the experimental data [5]. Developed in the present work methods of description of radiation in the D = 2 + 1 graphene permit direct generalization on the more complicated D = 3 + 1 situations [6, 7].
References
1. Smolyansky, S.A., Churochkin, D.V., Dmitriev, V.V., Panferov, A.D., Kampfer, B. EPJ Web of Conferences 138, 06004 (2017).
2. Smolyansky, S.A., Panferov, A.D., Blaschke, D.B., Gevorgyan, N.T. Particles 3(2), 456–476 (2020); arXiv:2004.03759.
3. Gavrilov, S., Gitman, D., Dmitriev, V., Panferov, A., Smolyansky, S. Universe 6, 205 (2020); arXiv:2010.10184v2.
4. Gavrilov, S., Gitman, D., Eur. Phys. J. Plus 138:171, (2023); arXiv:2210.03223v2.
5. Oladyshkin, I.V., Bodrov, S.B., Sergeev, Yu.A., Korytin, A.I., Tokman, M.D., Stepanov, A.N. Phys. Rev. B 96, 155401 (2017).
6. Smolyansky, S.A., Panferov, A.D., Pirogov, S.O., Fedotov, A.M. arXiv:1901.02305v1 (2019).
7. Prozorkevich, A.V., Smolyansky, S.A., Skokov, V.V., Zabrodin, E.E. Phys. Lett. B 583, 103 (2004).
A.T. D’yachenko$^{1,2}$
$^1$ Emperor Alexander I Petersburg State Transport University, St. Petersburg, 190031, Russia;
$^2$ B.P. Konstantinov Petersburg Nuclear Physics Institute National Research Center “Kurchatov Institute”, Gatchina, 188300, Russia
E-mail: dyachenko_a@mail.ru;
In the development of the nonequilibrium hydrodynamic approach [1, 2], we managed to completely describe the spectra of cumulative protons, pions and photons for the collision of carbon nuclei with a beryllium target in the energy range of 0.3-3.2 GeV per nucleon, obtained in the ITEP(Moscow) experiments. . When describing these spectra, the correction for the microcanonical distribution [1, 2] was taken into account, and the contribution of the fragmentation process was also taken into account for the proton yields [2]. Our description of the experimental data is better than the cascade models and the quantum molecular dynamics (QMD) model built into the GEANT4 package. In the present work, we have successfully described the double differential cross sections for the production of cumulative protons, pions, kaons, and antiprotons emitted at an angle of 0$^0$ for the collision of carbon nuclei in the $^{12}$C + $^{12}$C reaction at an energy of 19.6 GeV per nucleon on a fixed target, obtained at the U-70 accelerator at IHEP (Serpukhov) [3]. A comparison with other theoretical approaches is given. A connection between the equations of quantum hydrodynamics and the Klein-Gordon equation [4] is established, and approximate solutions of the equations of hydrodynamics are found using solitons in the one-dimensional and two-dimensional cases. Our approach is applicable to collisions of both light and heavy nuclei, which can be seen from a comparison with experimental data and other theoretical approaches based on solving the Boltzmann equation, the quantum molecular dynamics model, and etc. This can be extended to the energy range of the accusatory complex NICA located at JINR (Dubna).
$\bf{References}$
1. D’yachenko .A.T., Mitropolsky I.A., Phys. At. Nucl.$\bf{83}$, 558 (2020).
2. D’yachenko A.T., Mitropolsky I.A., Phys. At. Nucl. $\bf{85}$, 1053 (2022).
3. Afonin A.G. , Bogolubsky M.Yu., Volkov A.A. et al., Phys. At. Nucl. $\bf{83}$, 228 (2020).
4. D’yachenko A.T. Phys. At. Nucl. $\bf{86}$, 289 (2023).
The reactions $np \rightarrow np \pi^+ \pi^-$ was studied at the momenta of incident
neutrons $P_0$=3.83 and 5.20 GeV/c. There were calculated the contributions of various
diagrams (both of one-baryon and one-pion exchages) into the cross-section at the
momenta from the threshold up to 12 GeV/c. It was shown that the main contributions into
the reaction $np \rightarrow np \pi^+ \pi^-$ at the momenta above $P_0>$3 GEV/c
are provided by the diagrams of the reggeized $\pi$~exchange model (OPER).
The reeaction $np \rightarrow np \Delta^{++} \Delta^-$ was selected to study the spin
effect for $\Delta$-resonance decay. It was shown that the satisfactory description of
spin density matrix [$\rho_{ij}$] could be provided taking into account the diagram
of $\rho$-meson exchange. The reaction $np \rightarrow np \rho^0$ was selected using
the background subtraction. The study showed that the observed $\rho^0$ production is
provided by the 'hanged' diagram of OPER-model.\
The obtained results are in agreement with world data.
Negative binomial distribution for semi-inclusive distributions gives Hagedorn-Tsallis distribution for inclusive distributions. Radiating sourses counting rule in the hadronization phase, confining and statistical potentials for quarkonium systems in heavy ion scettering processies considered.
We discuss some new results in envisaged LUXE
experiment aims at studying strong-field QED
in electron-laser and photon-laser interactions, with
the 16.5 GeV electron beam of the European XFEL
and a laser beam with power of up to 350 TW.
We show some results for the non-linear Breit-Wheeler and Compton
processes. In particularly, we show prediction for electron-positron
production and discuss polarization observables in such processes.
The analysis of the new experimental data obtained by the TOTEM and ATLAS Collaborations at LHC together with old data, obtained at SPC and Tevatron colliders at small momentum transfer, in the framework of high energy generalized structure (HEGS) model allow to determined $s$ and $t$ dependence of the different parts of the hadron elastic scattering amplitude.
The study of the angular distribution of lepton pairs in hadronic collisions has allowed us to test the Drell-Yan mechanism[1, 2], as well as the interaction of vector W and Z bosons. However, rotationally invariant polarization expressions can provide more accurate measurements, improving the quality of comparisons between measurements and theoretical predictions [3, 4]. In all reference frames the angular coefficients are measured in the rest frame of the lepton pair. The angular distribution of the decay is determined by the choice of the polarization axis, i.e., by the choice of the direction of the 𝑧-axis of the rest frame of the 𝑍-boson. The reference frames differ only in the definition of the direction of the 𝑧-axis. In the literature, the Collins-Soper reference frame is most often used. In this paper we analyze the dependences of the rotational invariants on the transverse momentum 𝑞𝑇 in the Collins-Soper [5], Gottfried-Jackson [6], 𝑢–channel [7] reference frames.
Leptons are produced in decays of 𝑍 → 𝑙−𝑙+ gauge bosons born in proton-proton collisions in the Drell-Yan process. The measurement of lepton angular distributions allows us to study in detail the Drell-Yan process, in which a quark of one hadron and an antiquark of another hadron annihilate and, through the exchange of a 𝑍-boson or virtual photon 𝛾∗, create a pair of oppositely charged leptons 𝑙−𝑙+.
To estimate the errors of the rotational invariants it is necessary to calculate their standard deviation 𝜎 [8], for this purpose we used the characteristics of the coefficients 𝜆, 𝜇, 𝜈, whose functions are the rotational invariants.
The calculations were performed on the basis of data from the E615 experiment on the scattering of 𝜋−-mesons with energy 252 GeV on a fixed tungsten target. The result of checking the rotational invariants is their good agreement with the theory: the invariants are qualitatively closer than the coefficients of the angular distributions in different reference frames and lie within one standard deviation. We also analyze the rotational invariants with a zero coefficient 𝜇, the result of which is the appearance of a scatter of values of the rotational invariants, i.e., we can conclude about the non-zero value of this coefficient.
References
[1] S. D. Drell and T. M. Yan, “Massive Lepton Pair Production in Hadron-Hadron Collisions at High-Energies”, // Phys. Rev. Lett. 25, 316-320 1970 doi:10.1103/PhysRevLett.25.316
[2] V. A. Matveev, R. M. Muradian and A. N. Tavkhelidze, // Lett. Nuovo Cim. 7, 719-723 1973 doi:10.1007/BF02728133
[3] M. Gavrilova and O. Teryaev, // Phys. Rev. D 99 2019 no.7, 076013 doi:10.1103/PhysRevD.99.076013 [arXiv:1901.04018
[hep-ph]].
[4] P. Faccioli, C. Lourenco and J. Seixas, // Phys. Rev. Lett. 105 2010, 061601 doi:10.1103/PhysRevLett.105.061601 [arXiv:1005.2601 [hep-ph]].
[5] J. C. Collins and D. E. Soper, // Phys. Rev. D 16 1977, 2219 doi:10.1103/PhysRevD.16.2219
[6] K. Gottfried and J. D. Jackson, // Nuovo Cim. 33 1964, 309-330 doi:10.1007/BF02750195
[7] J. S. Conway, C. E. Adolphsen, J. P. Alexander, K. J. Anderson, J. G. Heinrich, J. E. Pilcher, A. Possoz, E. I. Rosenberg, C. Biino and J. F. Greenhalgh, et al. // Phys. Rev. D 39 1989, 92-122 doi:10.1103/PhysRevD.39.92
[8] Philip R. Bevington, D. Keith Robinson, Data reduction and error analysis for the physical sciences, // third edition ISBN 0-07-247227-8 2003
In the proton momentum range up to 3.5 GeV/c there are no intrinsic spin resonances and proton depolarization is associated with the crossing of integer spin resonances. Corrective dipoles are used to deliberately increase the strength of integer resonances by controlled deviation of the closed orbit. When the orbit is deviated up to 10 mm and the arch dipole field ramp rate is of 0.6 T/s, all integer resonances will cross adiabatically without loss of polarization apart from the first two resonances at energies of 108 and 631 MeV. At these energies the adiabatic crossover is provided by a weak solenoid with a field integral of 0.05 T m. External targets experiments and injections of polarized protons into the NICA collider up to 3.5 GeV/c will become feasible.
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. Due to its unique sensitivity and spatial resolution the used NTE method gives an opportunity to study in a unified approach multiple final states arising in the dissociation of relativistic nuclei. The aims to search in the relativistic approach for the $\alpha$-particle Bose-Einstein condensate ($\alpha$BEC), an unstable state of $S$-wave $\alpha$-particles. The extremely short-lived $^{8}$Be nucleus is described as 2$\alpha$BEC, and the $^{12}$C(0$^+_2$) excitation or Hoyle state (HS) as 3αBEC. The realizability of more complex states is essential in nuclear astrophysics.
Using NTE layers exposed longitudinally to relativistic nuclei the invariant mass of ensembles of He and H fragments can be determined over the emission angles in the approximation of conservation of initial momentum per nucleon. The $^8$Be and HS decays, as well as $^9$B $\to$ $^8$Be$p$ decays, are identified in fragmentation of light nuclei by an upper constraint on the invariant mass [1]. This approach has been used to identify $^8$Be and HS and search for more complex states of $\alpha$BEC in fragmentation of medium and heavy nuclei. Recently, based on the statistics of dozens of $^8$Be decays, an increase in the probability of detecting $^8$Be with an increase in the number of associated $\alpha$-particles $n\alpha$ was found [2]. The exotically large sizes and lifetimes of $^8$Be and HS suggest the possibility of synthesizing $\alpha$BEC by successively connecting the emerging $\alpha$-particles 2$\alpha$ $\to$ $^8$Be, $^8$Be$\alpha$ $\to$ $^{12}$C(0$^+_2$), $^{12}$C(0$^+_2$)$\alpha$ $\to$ $^{16}$O(0$^+_6$), 2$^8$Be $\to$ $^{16}$O(0$^+_6$) and further with a decreasing probability at each step, when $\gamma$-quanta or recoil particles are emitted. Ongoing investigation aims to measure $n\alpha$ channels of $^{84}$Kr fragmentation at energies up to 950 MeV per nucleon to determine the contributions of 2$\alpha$ decays of $^8$Be, the Hoyle 3$\alpha$ state, and the search for a 4$\alpha$ particle condensate state [3].
References
[1] D.A. Artemenkov et al., Eur. Phys. J. A 56 (2020) 250; arXiv: 2004.10277.
[2] A.A. Zaitsev et al., Phys. Lett. B 820 (2021) 136460; arXiv: 2102.09541.
[3] D.A. Artemenkov et al., Phys. At. Nucl., 85, 528 (2022); arХiv: 2206.09690.
Started in the late 1950th at DLNP JINR pioneering experimental studies of proton scattering on nuclei allowed D.I. Blokhintsev assumed the presence in nuclei a lower mass nucleus in a compressed state, i.e. the presence of a cold strongly compressed component in ordinary nuclear matter. The search and study of two- and three-nucleon systems in nuclei continued at DLNP JINR and ITEP (Moscow) and beyond. The huge interest in the study of multinucleon (multiquark) systems was initiated by the Baldin’s article appeared in 1971 where "cumulative processes" were predicted. The "cumulative processes" were discovered in experiments with accelerated deuteron beams at the LHE JINR in the same year. These investigations were carried out in the kinematic region, outside the kinematics of the nucleon-nucleon interaction. It is useful the processes in this kinematic region to call cumulative processes not look back on the theoretical models. The experimental data stimulated the emergence of many theoretical models that considered various multinucleon (multiquark) configurations in nuclei to explain the nature of the cumulative processes. Some considered various versions of multinucleon (multiquark) systems - fluctons, while others believed that nuclei contain point like nucleons with large relative momenta located at short distances (for example, short-range correlations - SRC). This report presents the nowadays situation of the cumulative process studies.
In this report the influence of relativistic rotation on QCD properties will be considered. This study is carried out within lattice simulation of QCD which is performed in the reference frame which rotates with the system under investigation. In this case rotation is reduced to external gravitational field. Within the report I am going to discuss the following topics: the influence of rotation on the confinement/deconfinement and breaking/restoration of chiral symmetry phase transitions, the moment of inertia and inhomegenious phase transitions in quark-gluon plasma.