Pseudoscalar mesons in nuclei and partial restoration of chiral symmetry

TL;DR

This paper reviews recent theoretical progress on how chiral symmetry is partially restored in nuclear matter, highlighting the role of in-medium hadronic modes, sum rules, and mesonic bound states in understanding fundamental QCD properties.

Contribution

It introduces a general sum rule linking in-medium hadronic properties with the quark condensate and discusses the significance of mesonic bound states and few-body systems in probing chiral symmetry restoration.

Findings

In-medium hadronic modes contribute to chiral condensate reduction.

Kaonic few-body systems reveal features of kaon-nucleus interactions.

Mesonic nuclei provide insights into chiral symmetry in baryons.

Abstract

Recent theoretical developments of hadrons in nuclei are briefly reviewed in the aspect of chiral symmetry in nuclei. We show a general sum rule connecting in-medium hadronic quantities and quark condensate, emphasizing that both pionic mode and particle-hole excitations in the nuclear medium are responsible for reduction of the chiral condensate in nuclear matter. We also discuss that few-body nuclear systems with kaons are good objects to investigate basic features of kaon-nucleus interactions, showing recent understandings of the structure of Lambda(1405) and possible bound states of KbarNN and KKbarN. We also mention eta mesonic nuclei in connection with chiral symmetry of baryons.