This work compares identified-hadron \(p_T\) spectra in Au+Au collisions at \(\sqrt{s}=7.7\) GeV, measured by the STAR experiment at RHIC, with results from common event generators. We use EPOS (EPOSLHC and EPOS4) and Pythia8 and confront them directly with the data. The study covers \(\pi ^\pm \) , \(K^\pm \) , and protons-antiprotons at mid-rapidity ( \(|y|<0.1\) ) in nine centrality bins.
Pythia8 tends to overestimate pion data and misrepresents kaons and (anti-)protons depending on centrality. EPOS4 described the pions spectra well in comparison with Pythia8 consistent with the inclusion of hadronic re-scattering in the model. EPOSLHC aligns with experimental data better at higher \(p_T\) for pions and anti-protons but underestimates kaons and protons in most centrality bins. At larger \(p_T\) , suppression is observed in EPOSLHC tune which may reflect the collective flow that affects high \(p_T\) particles. The EPOS4 model generally matches data well across centrality bins for \(\pi ^\pm \) , \(K^\pm \) mesons, and anti-protons, but its accuracy diminishes in peripheral collisions, particularly underestimating protons at high \(p_T\) consistent with weaker final-state interaction effects in smaller systems. Additionally, suppression is observed in EPOS4 in protons and anti-protons, which may be influenced by baryon–anti-baryon annihilation channels implemented in the model. In general, EPOS4 and EPOSLHC provide a closer description than Pythia8 in the measured range, consistent with their inclusion of collective dynamics and hadronic re-scattering. Additionally, the extracted freeze-out parameters show that effective temperature rises and the non-extensive parameter decreases with increasing centrality, indicating greater system excitation and faster thermal equilibration in central collisions.
