QCD Thermodynamics at Intermediate Coupling

TL;DR

This paper discusses the application of hard-thermal-loop perturbation theory (HTLpt) to improve the calculation of QCD thermodynamic functions at intermediate temperatures, showing better agreement with lattice data than traditional methods.

Contribution

It presents a NNLO HTLpt calculation of QCD thermodynamics, demonstrating improved convergence and consistency with lattice results at temperatures around twice the critical temperature.

Findings

NNLO HTLpt results align with lattice data at T~2T_c

Improved convergence over traditional weak-coupling expansion

Demonstrates gauge-invariant reorganization of perturbation theory

Abstract

The weak-coupling expansion of the QCD free energy is known to order g_s^6log{g_s}, however, the resulting series is poorly convergent at phenomenologically relevant temperatures. In this proceedings, I discuss hard-thermal-loop perturbation theory (HTLpt) which is a gauge-invariant reorganization of the perturbative expansion for gauge theories. I review a recent NNLO HTLpt calculation of QCD thermodynamic functions. I show that the NNLO HTLpt results are consistent with lattice data down to temperatures T~2T_c.