In-Medium Spectral Functions of Vector- and Axial-Vector Mesons from the Functional Renormalization Group

TL;DR

This paper investigates the in-medium spectral functions of vector and axial-vector mesons using the functional renormalization group, revealing chiral symmetry restoration effects at high temperature and chemical potential.

Contribution

It introduces a non-perturbative FRG approach with an analytic continuation method to study meson spectral functions in a low-energy effective theory.

Findings

Spectral functions degenerate at high temperature and chemical potential.

Chiral symmetry restoration causes spectral function degeneracy.

Momentum dependence of spectral functions analyzed.

Abstract

In this work we present first results on vector and axial-vector meson spectral functions as obtained by applying the non-perturbative functional renormalization group approach to an effective low-energy theory motivated by the gauged linear sigma model. By using a recently proposed analytic continuation method, we study the in-medium behavior of the spectral functions of the $\rho$ and $a_1$ mesons in different regimes of the phase diagram. In particular, we demonstrate explicitly how these spectral functions degenerate at high temperatures as well as at large chemical potentials, as a consequence of the restoration of chiral symmetry. In addition, we also compute the momentum dependence of the $\rho$ and $a_1$ spectral functions and discuss the various time-like and space-like processes that can occur.