Confinement order parameters and fluctuations

TL;DR

This paper uses the functional renormalisation group to compute confinement order parameters related to the Polyakov loop, achieving quantitative agreement with lattice results and highlighting deviations important for QCD models.

Contribution

It introduces a non-perturbative continuum approach to compute confinement order parameters and compares them with lattice results, revealing significant deviations near the phase transition.

Findings

Quantitative agreement with lattice results for the Polyakov loop

Significant deviations from standard continuum Polyakov loop near transition temperature

Implications for QCD effective models relying on Gaussian approximations

Abstract

We study order parameters for the confinement-deconfinement phase transition related to the Polyakov-loop variable. The functional renormalisation group is used to compute these order parameters in a unified, non-perturbative continuum approach. Our result for the expectation value of the traced Polyakov loop agrees quantitatively with the lattice result. Furthermore, we discuss how this order parameter differs from the standard continuum Polyakov loop. For temperatures close to the phase transition temperature there are significant deviations. We argue that these deviations are of crucial importance for QCD effective models, which usually implicitly rely on a Gaussian approximation neglecting this difference.