Nonequilibrium meson production in strong fields

TL;DR

This paper introduces a kinetic equation approach to model nonequilibrium meson production in strong, time-dependent fields, aiming to explain low-momentum pion enhancement observed in heavy-ion collisions.

Contribution

It presents a novel kinetic formalism for nonequilibrium meson production and explores the inertial mechanism's role in pion enhancement in heavy-ion collisions.

Findings

Strong low-momentum pion enhancement observed

Pion distribution approximates a thermal Bose distribution with chemical potential

Inertial mechanism can account for experimental observations

Abstract

We develop a kinetic equation approach to nonequilibrium pion and sigma meson production in a time-dependent, chiral symmetry breaking field (inertial mechanism). We investigate the question to what extent the low-momentum pion enhancement observed in heavy-ion collisions at CERN - LHC can be addressed within this formalism. In a first step, we consider the inertial mechanism for nonequilibrium production of $\sigma-$mesons and their simultaneous decay into pion pairs for two cases of $\sigma$ mass evolution. The resulting pion distribution shows a strong low-momentum enhancement which can be approximated by a thermal Bose distribution with a chemical potential that appears as a trace of the nonequilibrium process of its production.