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

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.