Dynamics of Chemical Equilibrium of Hadronic Matter Close to $T_c$

TL;DR

This paper explains rapid chemical equilibration of hadrons near the critical temperature using Hagedorn states, showing that hadrons reach equilibrium quickly and match experimental ratios, improving understanding of hadron gas dynamics.

Contribution

It introduces a dynamic model incorporating Hagedorn states to explain rapid chemical equilibration near $T_c$, aligning with lattice results and experimental data.

Findings

Hadrons reach chemical equilibrium almost immediately near $T_c$

Model matches experimental particle ratios

Consistent with lattice QCD results

Abstract

Quick chemical equilibration times of hadrons (specifically, $p\bar{p}$, $K\bar{K}$, $\Lambda\bar{\Lambda}$, and $\Omega\bar{\Omega}$ pairs) within a hadron gas are explained dynamically using Hagedorn states, which drive particles into equilibrium close to the critical temperature. Within this scheme, we use master equations and derive various analytical estimates for the chemical equilibration times. We compare our model to recent lattice results and find that for both $T_c=176$ MeV and $T_c=196$ MeV, the hadrons can reach chemical equilibrium almost immediately, well before the chemical freeze-out temperatures found in thermal fits for a hadron gas without Hagedorn states. Furthermore the ratios $p/\pi$, $K/\pi$, $\Lambda/\pi$, and $\Omega / \pi $ match experimental values well in our dynamical scenario.