Spectral properties of pseudo-scalar mesons through the QCD chiral crossover

Abstract

We summarise recent progress towards the non-perturbative determination of thermal spectral functions for pseudo-scalar mesons in QCD by exploiting constraints imposed by micro-causality at finite temperature. For temperatures not much above the vacuum particle mass, continuous contributions from scattering, Landau damping and collective excitations are found to be negligible. This allows for a quantitative description of spatial and temporal lattice correlators in terms of thermoparticles, i.e.~vacuum excitations modified by medium effects, with resonance-like structures persisting for a range above the chiral crossover.

Comments: 8 pages, 4 figures; contribution to the EMMI Workshop: "Aspects of Criticality II", 2-4 July 2024, Wroclaw, Poland