Baryons in the plasma: in-medium effects and parity doubling

TL;DR

This study uses lattice simulations to explore how baryon properties change in hot QCD matter, revealing temperature-dependent mass shifts and parity doubling, with implications for heavy-ion collision experiments.

Contribution

It provides the first nonperturbative lattice analysis of baryon in-medium effects and parity doubling across the QCD phase transition.

Findings

Negative-parity baryon masses decrease with temperature in the hadronic phase.

Parity doubling occurs at high temperature, indicating chiral symmetry restoration.

Stronger effects are observed for baryons containing strange quarks.

Abstract

We investigate the fate of baryons made out of u, d and s quarks in the hadronic gas and the quark-gluon plasma, using nonperturbative lattice simulations, employing the FASTSUM anisotropic Nf=2+1 ensembles. In the confined phase a strong temperature dependence is seen in the masses of the negative-parity groundstates, while the positive-parity groundstate masses are approximately temperature independent, within the error. At high temperature parity doubling emerges. A noticeable effect of the heavier s quark is seen. We give a simple description of the medium-dependent masses for the negative-parity states and speculate on the relevance for heavy-ion phenomenology via the hadron resonance gas.