Symmetries of the light hadron spectrum in high temperature QCD

TL;DR

This study investigates how chiral and axial symmetries manifest in the baryon spectrum of high-temperature QCD, exploring potential emergent symmetries near the chiral crossover.

Contribution

It constructs specific operators to analyze chiral and $U(1)_A$ symmetries in baryons at high temperature, using lattice QCD with domain-wall fermions.

Findings

Evidence for symmetry restoration in baryon spectrum

Analysis of volume and quark-mass dependence

Discussion of emergent $SU(4)$ and $SU(2)_{CS}$ symmetries

Abstract

Properties of QCD matter change significantly around the chiral crossover temperature, and the effects on $U(1)_A$ and topological susceptibilities, as well as the meson spectrum have been studied with much care. Baryons and the effect of parity doubling in this temperature range have been analyzed previously by various other groups employing different setups. Here we construct suitable operators to investigate chiral and axial $U(1)_A$ symmetries in the baryon spectrum. Measurements for different volumes and quark-masses are done with two flavors of chirally symmetric domain-wall fermions at temperatures above the critical one. The possibility of emergent $SU(4)$ and $SU(2)_{CS}$ symmetries is discussed.