Partial restoration of chiral symmetry and pion in nuclear medium

TL;DR

This paper explores how chiral symmetry is partially restored in nuclear matter, analyzing the in-medium quark condensate and deriving related relations using chiral perturbation theory.

Contribution

It introduces a derivation of the in-medium Weinberg-Tomozawa relation and examines the density dependence of the quark condensate beyond linear approximation.

Findings

Density dependence of quark condensate includes vertex corrections and nucleon correlations.

Partial chiral symmetry restoration occurs in nuclear medium.

Chiral perturbation theory effectively describes in-medium quark condensate changes.

Abstract

We discuss partial restoration of chiral symmetry in nuclear medium, which is realized as an effective reduction of the quark condensate in nuclear medium. We derive the in-medium Weinberg-Tomozawa relation. We also give a brief calculation of the in-medium quark condensate based on chiral perturbation theory. We conclude that the density dependence of the quark condensate beyond the linear density comes from the vertex correction of the chiral field insertion and nucleon correlations.