Spectral function for overoccupied gluodynamics from real-time lattice simulations

TL;DR

This paper investigates the spectral properties of a highly occupied non-equilibrium gluon plasma using real-time lattice simulations, revealing quasiparticle characteristics and extending HTL theory non-perturbatively.

Contribution

It introduces a non-perturbative method to measure spectral functions in non-equilibrium QCD matter, generalizing the HTL effective theory beyond its traditional limits.

Findings

Identification of transversely and longitudinally polarized quasiparticles

Determination of dispersion relations, effective mass, and damping rates

Indications that results approach leading order HTL in certain limits

Abstract

We study the spectral properties of a highly occupied non-Abelian non-equilibrium plasma appearing ubiquitously in weak coupling descriptions of QCD matter. The spectral function of this far-from-equilibrium plasma is measured by employing linear response theory in classical-statistical real-time lattice Yang-Mills simulations. We establish the existence of transversely and longitudinally polarized quasiparticles and obtain their dispersion relations, effective mass, plasmon frequency, damping rate and further structures in the spectral and statistical functions. Our new method can be interpreted as a non-perturbative generalization of hard thermal loop (HTL) effective theory. We see indications that our results approach leading order HTL in the appropriate limit. The method can also be employed beyond the range of validity of HTL.