On the smallest screening masses in hot QCD

TL;DR

This paper investigates the theoretical structure of the smallest gluonic screening mass in hot QCD, showing that its next-to-leading order correction is small, which explains its behavior at moderate temperatures.

Contribution

It provides a perturbative analysis of the smallest screening mass in hot QCD, clarifying its theoretical properties and temperature dependence.

Findings

Next-to-leading order correction is perturbative and small.

The smallest screening mass couples to energy density and Polyakov loop.

This mass explains the dominant length scale at a few hundred MeV.

Abstract

The increasing focus on unquenched lattice simulations has revived interest also in gluonic screening masses, whose inverses characterise the longest length scales at which thermal fluctuations are correlated in a hot non-Abelian plasma. We fill an apparent gap in the literature concerning the theoretical structure of one of the relevant screening masses (the one which equals twice the Debye mass at leading order), by showing that the next-to-leading order correction to it is perturbative and small. This surprising result appears to explain semi-quantitatively why this particular channel yields the smallest gluonic screening mass at temperatures around a few hundred MeV (it couples to the energy density and to the real part of the Polyakov loop), even though it is not among the smallest screening masses at asymptotically high temperatures.