Effect of spectral modification of $\rho$ on shear viscosity of a pion gas

TL;DR

This paper investigates how modifications to the $ ho$ meson spectral function influence the shear viscosity of a pion gas, using in-medium propagators and kinetic theory to analyze temperature-dependent effects.

Contribution

It introduces a detailed analysis of in-medium $ ho$ meson effects on pion scattering and shear viscosity, combining spectral modifications with kinetic theory approaches.

Findings

Spectral modifications significantly affect shear viscosity calculations.

Real and imaginary parts of the $ ho$ self-energy alter scattering cross-sections.

Temperature dependence of shear viscosity is sensitive to in-medium effects.

Abstract

We evaluate the shear viscosity of a pion gas in the relativistic kinetic theory approach. The in-medium propagator of the $\rho$ meson at finite temperature is used to evaluate the $\pi-\pi$ scattering amplitude in the medium. The real and imaginary parts of the self-energy calculated from one-loop diagrams are seen to have noticeable effects on the scattering cross-section. The consequences on temperature dependence of the shear viscosity evaluated in the Chapman-Enskog and relaxation time approximations are studied.