Single quark entropy and the Polyakov loop

TL;DR

This paper investigates the behavior of the Polyakov loop, free energy, and entropy of a single static quark in QCD with nearly physical quark masses, revealing insights into the crossover and deconfinement phenomena.

Contribution

It provides a detailed analysis of the entropy peak near the chiral crossover and the onset of weak coupling at high temperatures in QCD with 2+1 flavors.

Findings

Entropy peaks near the chiral crossover

Polyakov loop susceptibilities relate to the crossover

Weak coupling behavior begins at high temperatures

Abstract

We study Quantum Chromodynamics (QCD) with 2+1 flavors with almost physical quark masses using the highly improved staggered quark action (HISQ). We calculate the Polyakov loop in a wide temperature range, obtain the free energy and the entropy of a single static quark and discuss the QCD crossover region in detail. We show that the entropy has a peak close to the chiral crossover and consider the consequences for the deconfinement aspects of the crossover phenomena. We study the renormalized Polyakov loop susceptibilities and place them into the context of the crossover. We also obtain a quantitative result for the onset of weak coupling behavior at high temperatures.