Fermion and gluon spectral functions far from equilibrium

TL;DR

This paper introduces a non-perturbative simulation method to compute fermion spectral functions in a far-from-equilibrium non-Abelian plasma, revealing detailed momentum-dependent damping rates and validating results against perturbative and other non-perturbative approaches.

Contribution

Develops a novel simulation technique to extract fermion spectral functions in non-Abelian gauge theories far from equilibrium, including full momentum dependence.

Findings

Good agreement with perturbative HTL calculations.

First extraction of full momentum-dependent fermionic damping rates.

Comparison with gluonic spectral functions shows consistency.

Abstract

Motivated by the quark-gluon plasma, we develop a simulation method to obtain the spectral function of (Wilson) fermions non-perturbatively in a non-Abelian gauge theory with large gluon occupation numbers [arXiv:2106.11319]. We apply our method to a non-Abelian plasma close to its non-thermal fixed point, i.e., in a far-from-equilibrium self-similar regime, and find mostly very good agreement with perturbative hard loop (HTL) calculations. For the first time, we extract the full momentum dependence of the damping rate of fermionic collective excitations and compare our results to recent non-perturbative extractions of gluonic spectral functions in two and three spatial dimensions [arXiv:2101.02715, arXiv:1804.01966].