Speaker
Description
One of the important goals of the PHENIX ($\sqrt{s_{NN}}$ = 200 GeV) and upcoming MPD $\sqrt{s_{NN}}$ = 9.2 GeV experiments is to study QCD phase transition and to investigate possible QGP formation in small collision systems (in the case of PHENIX) or at low energies (in the case of MPD).
With that purpose PHENIX provided a comprehensive study of identified charged hadron production ($\pi^{\pm}$, $K^{\pm}$, $p$, $\bar{p}$) in $p$+Al, $^3$He+Au, Cu+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV and U+U collisions at $\sqrt{s_{NN}}$ = 193 GeV. Meanwhile, the upcoming MPD experiment is focused on studying charged hadron production in Bi+Bi collisions at $\sqrt{s_{NN}}$ = 9.2 GeV, based on UrQMD simulations.
Identified charged hadron invariant transverse momentum ($p_T$) and transverse mass ($m_T$) spectra obtained from both PHENIX and MPD experiments were analyzed using the Blast-Wave model, which allowed to estimate the freeze-out temperatures and radial flow velocities.
The nuclear modification factors and particle yield ratios, $K/\pi$ and $p/\pi$, are systematically studied across different centrality classes in both small ($p$+Al, $^3$He+Au) and large (Cu+Au, U+U) collision systems. This analysis provided estimates of the contributions from fragmentation and recombination processes to charged hadron production at the PHENIX energy. To gain a deeper insight, the experimental results are compared with theoretical predictions from the AMPT and PYTHIA8/ANGANTYR models. Additionally, the study of $p/\pi$ ratios measured in Bi+Bi collisions at the MPD experiment enabled the calculation of the chemical freeze-out temperature and the corresponding baryon chemical potential for the MPD energy regime.
The results obtained from PHENIX and MPD are compared and summarized in the context of the QCD phase diagram.
We acknowledge support from Russian Ministry of Education and Science. State assignment for fundamental research (code FSEG-2025-0009).
