Recent progress in hard-thermal-loop QCD thermodynamics and collective excitations

TL;DR

This paper reviews recent advances in hard-thermal-loop QCD thermodynamics, including NNLO calculations and the discovery of a new massless mode, addressing open questions from heavy-ion collision experiments.

Contribution

It introduces a generalized hard-thermal-loop framework at the magnetic scale, revealing a novel massless excitation in QCD at finite temperature and density.

Findings

NNLO QCD thermodynamics calculation using hard-thermal-loop perturbation theory

Identification of a new massless mode at the magnetic scale

Insights into collective excitations relevant for heavy-ion collisions

Abstract

I review recent developments in QCD thermodynamics and collective excitations from the hard-thermal-loop effective theory. I begin by motivating the discussion with open questions from heavy-ion collisions. I then discuss a finite-temperature and -density calculation of QCD thermodynamics at NNLO from the hard-thermal-loop perturbation theory. Finally I discuss a recent exploration of generalizing the hard-thermal-loop framework to the (chromo)magnetic scale $g^2T$, from which a novel massless mode is uncovered.