Nucleons and parity doubling across the deconfinement transition

TL;DR

This study uses lattice QCD simulations to investigate parity doubling of nucleons across the deconfinement transition, finding clear signs of degeneracy in the quark-gluon plasma and temperature-dependent effects in the negative-parity channel.

Contribution

It provides the first lattice QCD evidence of parity doubling in the deconfined phase and analyzes temperature effects on nucleon states.

Findings

Parity doubling observed in quark-gluon plasma

Nucleon ground state largely temperature-independent

Significant temperature effects in negative-parity channel

Abstract

It is expected that nucleons and their parity partners become degenerate when chiral symmetry is restored. We investigate this question in the context of the thermal transition from the hadronic phase to the quark-gluon plasma, using lattice QCD simulations with N_f=2+1 flavours. We observe a clear sign of parity doubling in the quark-gluon plasma. Besides, we find that the nucleon ground state is, within the uncertainty, largely independent of the temperature, whereas temperature effects are substantial in the negative-parity (N^*) channel, already in the confined phase.