Chiral Transition in QCD and Scalar Correlations

TL;DR

This paper reviews recent research on chiral symmetry restoration in nuclear matter, focusing on scalar spectral functions, pion wave function renormalization, and the movement of the sigma meson pole.

Contribution

It highlights the importance of pion wave function renormalization and the sigma meson pole movement as indicators of chiral symmetry restoration in nuclear medium.

Findings

Pion decay constant decreases as chiral symmetry is restored.

Sigma meson pole approaches the origin in the complex plane.

Scalar spectral function reflects partial chiral symmetry restoration.

Abstract

We review recent developments in exploring possible precursory phenomena of partial restoration of chiral symmetry in nuclear medium by examining the spectral function in the scalar channel. We emphasize that the wave function renormalization of the pion in the medium plays an essential role to induce the decrease of the pion decay constant as the order parameter of chiral transition. We also show that the $\sigma$ meson pole in the complex energy plane moves toward the origin as chiral symmetry is restored in hot and/or dense nuclear matter.