QCD mesonic screening masses and restoration of chiral symmetry at high T

TL;DR

This paper introduces a non-perturbative lattice approach to study QCD at very high temperatures, revealing detailed mesonic screening mass behavior and chiral symmetry restoration up to the electroweak scale.

Contribution

It develops a finite-volume, non-perturbative definition of the strong coupling to analyze QCD at high temperatures and computes mesonic screening masses across a wide temperature range.

Findings

Mass splitting between vector and pseudoscalar persists up to the electroweak scale.

Chiral symmetry restoration is evidenced by degeneracy of pseudoscalar/scalar and vector/axial-vector channels.

Screening spectrum shows features not explained by 1-loop perturbation theory.

Abstract

We present a strategy to study QCD non-perturbatively on the lattice at very high temperatures. This strategy exploits a non-perturbative, finite-volume, definition of the strong coupling constant to renormalize the theory. As a first application we compute the flavor non-singlet mesonic screening masses in a wide range of temperature, from $T\sim 1 $ GeV up to $\sim 160 $ GeV with three flavors in the chiral limit of QCD. Our results show very interesting features of the screening spectrum at very high temperatures. On one hand the mass splitting between the vector and the pseudoscalar screening masses is clearly visible up to the electroweak scale and cannot be explained by the known 1-loop perturbative result. On the other hand the restoration of chiral symmetry manifests itself through the degeneracy of the pseudoscalar and the scalar channels and of the vector and the axial-vector ones. This degeneracy pattern is the one expected by Ward identities associated to the presence of chiral symmetry.