Spectral function of fermions in a highly occupied non-Abelian plasma

TL;DR

This paper introduces a non-perturbative method to compute fermion spectral functions in a highly occupied non-Abelian plasma, revealing detailed quasiparticle properties and damping rates in a non-equilibrium setting.

Contribution

The authors develop a novel non-perturbative approach to determine fermion spectral functions in non-Abelian gauge theories with high gauge field occupation.

Findings

Good agreement with hard loop perturbation theory for medium-induced masses

Extraction of dispersion relations and quasiparticle residues

Full momentum dependence of damping rates obtained

Abstract

We develop a method to obtain fermion spectral functions non-perturbatively in a non-Abelian gauge theory with high occupation numbers of gauge fields. After recovering the free field case, we extract the spectral function of fermions in a highly occupied non-Abelian plasma close to its non-thermal fixed point, i.e., in a self-similar regime of the non-equilibrium dynamics. We find good agreement with hard loop perturbation theory for medium-induced masses, dispersion relations and quasiparticle residues. We also extract the full momentum dependence of the damping rate of the collective excitations.