Does the QCD plasma contain propagating gluons?

TL;DR

This paper investigates whether the quark-gluon plasma contains propagating gluons by analyzing screening masses, revealing a transition from glueball-like modes near the critical temperature to gluon-like quasi-particles at higher temperatures.

Contribution

It provides evidence for the existence of propagating gluons in the QCD plasma and describes the transition between glueball-like and gluon-like excitations across temperatures.

Findings

Presence of a weakly-interacting massive gluon-like mode at high T

Continuity between glueball-like and gluon-like regimes near T_c

Mass ratios suggest a smooth transition in excitation modes

Abstract

Comparison of two appropriately chosen screening masses of colour singlet operators in the pure glue QCD plasma indicates that at sufficiently high temperature it contains a weakly-interacting massive quasi-particle with the quantum numbers of the electric gluon. Still in the deconfined phase, but closer to T_c, the same mass ratio is similar to that at zero temperature, indicating that the propagating modes are more glueball-like, albeit with a lower scale for the masses. We observe a continuity between these two regimes.