Hadronic resonance gas and charged particle's $p_T$ spectra and elliptic flow in $\sqrt{s}$=200 GeV Au+Au collisions

TL;DR

This study uses a hydrodynamic model with a hot hadronic resonance gas to analyze charged particle spectra and elliptic flow in Au+Au collisions at 200 GeV, revealing the importance of viscosity variations with collision centrality.

Contribution

It introduces a hydrodynamic approach incorporating a hot resonance gas with specific initial conditions to explain experimental data on spectra and flow.

Findings

Resonance gas model fits $p_T$ spectra across centralities.

Elliptic flow requires increasing viscosity with centrality.

Viscosity to entropy ratio varies with collision centrality.

Abstract

Charged particles $p_T$ spectra and elliptic flow in 0-60% Au+Au collisions at RHIC are analyzed in a hydrodynamic model with hot, hadronic resonance gas in the initial state. Physically conceivable hadronic resonance gas, thermalized in the time scale $\tau_i$=1 fm, at a (central) temperature $T_i$=220 MeV, with viscosity to entropy ratio $\eta/s$=0.24, reasonably well explains $p_T$ spectra in all the collision centralities. Centrality dependence of elliptic flow however demands continual increase of viscosity to entropy ratio with centrality.