Determining Transport Coefficients for a Microscopic Simulation of a Hadron Gas

TL;DR

This paper develops methods to extract transport coefficients like shear viscosity from microscopic simulations of a hadron gas, enhancing understanding of the hadronic phase in heavy-ion collisions.

Contribution

It introduces new techniques to determine transport properties from simulations, linking microscopic dynamics to hydrodynamic parameters.

Findings

Transport coefficients are extracted successfully from simulations.

Results align with theoretical expectations based on Kubo relations.

Provides a framework for studying hadronic matter in heavy-ion collisions.

Abstract

Quark-Gluon plasmas produced in relativistic heavy-ion collisions quickly expand and cool, entering a phase consisting of multiple interacting hadronic resonances just below the QCD deconfinement temperature, $T\sim 155$ MeV. Numerical microscopic simulations have emerged as the principal method for modeling the behavior of the hadronic stage of heavy-ion collisions, but the transport properties that characterize these simulations are not well understood. Methods are presented here for extracting the shear viscosity, and two transport parameters that emerge in Israel-Stewart hydrodynamics. The analysis is based on studying how the stress-energy tensor responds to velocity gradients. Results agree with expectations based on Kubo relations.