Computation of QCD meson screening masses at high temperature

TL;DR

This study calculates meson screening masses in high-temperature QCD across a wide temperature range, revealing small deviations from free theory and persistent non-perturbative effects up to the electroweak scale.

Contribution

It provides high-precision lattice QCD results for meson screening masses at temperatures up to the electroweak scale, with continuum extrapolation and analysis of chiral symmetry restoration.

Findings

Screening masses deviate minimally from $2\pi T$

Perturbation theory cannot fully explain the results at high temperatures

Chiral symmetry restoration is evidenced by degeneracy of certain meson channels

Abstract

We compute flavor non-singlet meson screening masses in the chiral limit of QCD with $N_f=3$ quarks. The calculation is carried out at 12 temperatures from $T\approx 1$ GeV up to the electroweak scale. For each temperature we simulated several lattice spacings, so as to be able to perform the continuum limit extrapolation with confidence at a few permille accuracy. In the entire range of temperatures explored, the meson screening masses deviate from the free theory result $2\pi T$ by at most a few percent. Their values, however, cannot be explained by one-loop perturbation theory up to the electroweak scale, where the pseudoscalar and the vector screening masses are still significantly different within our precision. Chiral symmetry restoration manifests itself through the degeneracy of the pseudoscalar and the scalar channels and of the vector and the axial ones.