Speaker
Description
The direct photon production in proton-proton collisions, both inclusive and heavy-meson-associated, is an important source of information on gluon distribution function inside the proton. Through the studies of transverse single-spin and double longitudinal asymmetries in polarized-beam collisions one can extract the information of the spin gluon content [1,2]. Since the study of direct photon production is one of the important tasks of the physical program at Spin Physics Detector (SPD) at NICA Collider [3] one faces a problem to recognize the direct photons from the background. Primary decay photons from pi0 would be a main source of the background to direct photons at NICA energies of sqrt S = 27 GeV and sqrt S = 20 GeV.
At first step in our work we study the set of existing data in pp colisions at energies from19.4 GeV to 630 GeV on direct photon and pi0 inclusive production. We calculate the inclusive neutral pion and photon production diferential cross sections in the leading order of Particle Reggeization Approach [4] to extract the NLO to LO K-factors. Then we simulate these spectra using Pythia8 to obtain photon-to-neutral pion ratios.
At the next step we simulate the spectra of decay photon candidates at NICA energies on different kinematic variables to obtain the form of distributions, which allow us to apply a number of cuts to distinguish signal events from pi0 decay background at the generator level. Finally we propose the cuts which increase significantly the signal to background ratio.
[1] Saleev V.A., Shipilova A.V. Double Longitudinal-Spin Asymmetries in Direct Photon Production at NICA // Physics of Particles and Nuclei Letters 2023. — Vol. 20. Issue 3. № 3. — P. 400-403.
[2] Saleev V.A., Shipilova A.V. Gluon Sivers Function in Transverse Single-Spin Asymmetries of Direct Photons at NICA // PHYSICS OF ATOMIC NUCLEI 2022. — Vol. 85. Issue 6. № 6. — P. 737-747.
[3] Arbuzov A., Bacchetta A., Butenschoen M., Celiberto F. G. On the physics potential to study the gluon content of proton and deuteron at NICA SPD // Progress in Particle and Nuclear Physics 2021. – Volume 119. – P.103858.
[4] A. V. Karpishkov and V. A. Saleev Production of three isolated photons in the parton Reggeization approach at high energies // Phys. Rev. D. – Vol. 106. – P. 054036.
