Speaker
Description
The production of identified charged particles ($\pi^{\pm}$, $K^{\pm}$, $p(\overline{p})$) in Pb$-$Pb collisions at $\sqrt{s_{\mathrm{NN}}} = 5.02~\mathrm{TeV}$ is investigated using the EPOS4 model. Two configurations are examined: EPOS4 with and without the Ultra-relativistic Quantum Molecular Dynamics (UrQMD) hadronic transport, allowing isolation of late-stage hadronic effects. Charged-particle multiplicity ($\mathrm{d}N_{\mathrm{ch}}/\mathrm{d}\eta$), transverse momentum ($p_{\mathrm{T}}$) spectra, $p_{\mathrm{T}}$-differential and integrated yield ratios ($K/\pi$, $p/\pi$) are studied to explore the underlying dynamics of particle production. Low-$p_{\mathrm{T}}$ behavior is found to be dominated by hadronic rescattering and strangeness enhancement, evident from the centrality-dependent increase in the $K/\pi$ ratio. At intermediate $p_{\mathrm{T}}$, a baryon-to-meson enhancement in the $p/\pi$ ratio is observed, consistent with radial flow and quark recombination mechanisms. EPOS4 with UrQMD demonstrates improved agreement with experimental data from the ALICE collaboration, particularly in describing radial flow, and the shape of identified hadron spectra. The hadronic afterburner plays a significant role in modifying spectral shapes via baryon-antibaryon annihilation and resonance decays, demonstrating its necessity for accurate modeling of the hadronic phase. Overall, EPOS4, especially with UrQMD, provides a quantitative and coherent description of centrality and mass‑dependent features of charged‑particle production, highlighting the essential role of late‑stage hadronic dynamics in shaping spectra and yields.