Examining hadronic resonance dynamics at energies available at the CERN Large Hadron Collider: Insights from EPOS4

Abstract

Hadronic resonances, with lifetimes of a few $\mathrm{fm}/c$, are key tools for studying the hadronic phase in high-energy collisions. This work investigates resonance production in pp collisions at $\sqrt{s}=13.6~\mathrm{TeV}$ and Pb--Pb collisions at $\sqrt{s_{\mathrm{NN}}}=5.36~\mathrm{TeV}$ using the EPOS4 model. By switching the Ultra-Relativistic Quantum Molecular Dynamics (UrQMD) hadronic afterburner ON or OFF, EPOS4 enables the study of final-state hadronic interactions. The production of strange and non-strange hadrons is also investigated using transverse momentum ($p_{\mathrm{T}}$) spectra and particle ratios to study rescattering, regeneration, baryon-to-meson production, and strangeness enhancement. Rescattering effects and strangeness enhancement dominate the low-$p_{\mathrm{T}}$ region, while enhanced baryon-to-meson yield ratios and strong mass-dependent radial flow are observed at intermediate $p_{\mathrm{T}}$ in central Pb--Pb collisions. The average $p_{\mathrm{T}}$ scaled by the reduced hadron mass deviates from a linear trend for short-lived resonances, indicating hadronic phase effects. The hadronic phase lifetime ($τ$), estimated from yield ratios of short-lived resonances to stable hadrons, increases with charged-particle multiplicity and system size, while remaining non-zero in high-multiplicity pp collisions. The production of non-strange (p), strange ($Λ$), and multi-strange ($Ξ$, $Ω$) baryons in central Pb--Pb collisions is governed by the competing effects of strangeness enhancement and baryon--antibaryon annihilation. These results provide valuable insights into the hadronic phase and particle production at LHC energies.