Chiral condensate at finite density using chiral Ward identity

Understand

In order to study partial restoration of the chiral symmetry at finite density, we investigate the density corrections of the chiral condensate up to next-leading order of density expansion using the chiral Ward identity and an in-medium chiral perturbation theory.

• In our study, we assume that all the in-vacuum quantities for the pion, the nucleon and the pi N interaction are determined and focus on density expansion of the in-medium physical quantities.
• We perform diagrammatic analysis of the correlation functions which provide the in-medium chiral condensate.
• This density expansion scheme shows that medium effects to the chiral condensate beyond the linear density come from density corrections to the pi N sigma term as a result of the interactions between pion and nucleon in nuclear matter.