QCD pressure: renormalization group optimized perturbation theory confronts lattice

TL;DR

This paper applies renormalization group optimized perturbation theory to evaluate the quark contribution to QCD pressure, achieving results that agree well with lattice data and reducing scale dependence issues present in standard methods.

Contribution

It introduces RGOPT for QCD pressure calculations, providing improved accuracy and reduced scale dependence compared to traditional perturbative approaches.

Findings

RGOPT results align with lattice QCD data for 0.25 to 1 GeV temperatures.

Significant reduction in scale dependence with RGOPT.

NLO quark contribution combined with gluon pressure yields accurate total pressure.

Abstract

The quark contribution to the QCD pressure, $P_q$, is evaluated up to next-to-leading order (NLO) within the renormalization group optimized perturbation theory (RGOPT) resummation approach. To evaluate the complete QCD pressure we simply add the perturbative NLO contribution from massless gluons to the resummed $P_q$. Despite of this unsophisticated approximation our results for $P = P_q +P_g$ at the central scale $M\sim 2\pi T$ show a remarkable agreement with ab initio lattice predictions for $0.25 \lesssim T \lesssim 1 \, {\rm GeV}$. We also show that by being imbued with RG properties, the RGOPT produces a drastic reduction of the embarrassing remnant scale dependence that plagues both standard thermal perturbative QCD and hard thermal loop perturbation theory (HTLpt) applications.