Plasmon mass scale in two dimensional classical nonequilibrium gauge theory

TL;DR

This paper investigates the plasmon mass scale in a two-dimensional nonabelian gauge theory mimicking heavy ion collision conditions, using numerical methods to compare different measurement techniques and analyze time evolution.

Contribution

It introduces and compares three methods for measuring the plasmon mass scale in a 2D gauge theory and studies its time dependence and occupation number effects.

Findings

Hard thermal loop and electric field methods roughly agree

Effective dispersion relation matches within a factor of two

Plasmon mass squared decreases as t^(-1/3) at late times

Abstract

We study the plasmon mass scale in weakly coupled strongly interacting nonabelian gauge theory in a two dimensional configuration that mimics the boost invariant initial color fields in a heavy ion collision. We numerically measure the plasmon mass scale using three different methods: a Hard Thermal Loop (HTL) expression involving the quasiparticle spectrum constructed from Coulomb gauge field correlators, an effective dispersion relation and the measurement of oscillations between electric and magnetic energies after introducing a spatially uniform perturbation to the electric field. We find that the hard thermal loop expression and the uniform electric field measurement are in rough agreement. The effective dispersion relation agrees with other methods within a factor of two. We also study the dependence on time and occupation number, observing similar trends as in three spatial dimensions, where a power law dependence sets in after an occupation number dependent transient time. We observe a decrease of the plasmon mass squared as $t^{\frac{-1}{3}}$ at late times.