Spectral functions and in-medium properties of hadrons

TL;DR

This paper reviews how hadronic spectral properties change in hot and dense environments, linking these modifications to chiral symmetry restoration, and highlights experimental signals observed in heavy-ion collisions.

Contribution

It provides a comprehensive overview of recent theoretical and experimental advances in understanding in-medium hadron properties and their relation to chiral symmetry restoration.

Findings

Spectral functions are modified at finite temperature and density.

Experimental di-lepton signals support in-medium modifications.

Chiral symmetry restoration is connected to spectral changes.

Abstract

The in-medium modifications of hadron properties such as masses and decay widths have been a major focus of the scientific work of Gerry Brown and the insights gained by him and his collaborators made them major drivers of this field for several decades. Their prediction of experimental signals in di-lepton pair production in relativistic heavy-ion collisions were instrumental in initiating large experimental campaigns which continue until today. In this chapter we review recent results which elucidate the relation of hadronic spectral properties at finite temperature and density to the restoration of spontaneously broken chiral symmetry.