Anomaly-induced Chiral Mixing in Cold and Dense Matter

TL;DR

This paper investigates how baryon density induces mixing between parity partners of light vector mesons, affecting their spectral functions and providing observable signatures of chiral symmetry restoration in dense matter.

Contribution

It introduces a novel baryon-density-induced chiral mixing mechanism affecting vector meson spectral functions at finite density and temperature.

Findings

Spectral functions show significant signatures of chiral symmetry restoration.

Baryon resonances and kaon modifications contribute to in-medium broadening.

Lepton pair production rates reflect chiral symmetry effects.

Abstract

We construct the spectral functions for light vector mesons at finite density and temperature in the presence of a novel mixing between parity partners, induced by baryon density via the Wess-Zumino-Witten action. As the main origin of in-medium broadening, a set of baryon resonances that strongly couple to the vector mesons and the modifications of kaons and anti-kaons due to the Kaplan-Nelson term are included. It is shown that the vector spectra, even with the broadening effects, exhibit sizable signatures of chiral symmetry restoration thanks to the chiral mixing depending on three-momenta carried by the vector mesons. Those spectral functions are used to calculate the integrated production rates of lepton pairs, and a proper binning in momenta and potential decrease in the vector-meson masses due to chiral symmetry restoration are discussed in quantifying the signatures.