Pion damping width and pion spectral function in hot pion gas

TL;DR

This paper investigates how the pion damping width and spectral function change with temperature in a hot pion gas using the NJL model, highlighting significant broadening at temperatures above 0.1 GeV.

Contribution

It introduces a detailed calculation of the pion width and spectral function in hot pion gas considering pion-pion collisions with sigma-meson intermediates, using the Kadanoff-Baym method.

Findings

Pion width broadens significantly above 0.1 GeV.

Spectral function calculations show temperature-dependent modifications.

The model provides insights into hadronic phase properties at finite temperature.

Abstract

The temperature behaviour of the pion width in the hadronic phase is investigated in the framework of the NJL model. The contribution to the width from the pion-pion collision is considered with a scalar sigma-meson as an intermediate state. It is shown that the pion width significantly broadens at $T>0.1$ GeV. Using the two-step iteration method, suggested by Kadanoff and Baym, the pion spectral function in a hot pion gas is calculated at different temperatures.