Chiral Mirror-Baryon-Meson Model and Nuclear Matter beyond Mean-Field

TL;DR

This paper extends a chiral baryon-meson model for nuclear matter by including mesonic fluctuations via the functional renormalization group, revealing a robust first-order chiral transition at high densities beyond mean-field approximations.

Contribution

It introduces a beyond mean-field approach to the chiral baryon-meson model using the functional renormalization group, analyzing the impact of mesonic fluctuations on the phase diagram.

Findings

Mesonic fluctuations do not significantly alter the phase diagram.

Parameter adjustments become constrained when including fluctuations.

A robust first-order chiral transition persists at high baryon densities.

Abstract

We consider a chiral baryon-meson model for nucleons and their parity partners in mirror assignment interacting with pions, sigma and omega mesons to describe the liquid-gas transition of nuclear matter together with chiral symmetry restoration in the high density phase. Within the mean-field approximation the model is known to provide a phenomenologically successful description of the nuclear-matter transition. Here, we go beyond this approximation and include mesonic fluctuations by means of the functional renormalization group. While these fluctuations do not lead to major qualitative changes in the phase diagram of the model, beyond mean-field, one is no-longer free to adjust the parameters so as to reproduce the binding energy per nucleon, the nuclear saturation density, and the nucleon sigma term all at the same time. However, the prediction of a clear first-order chiral transition at low temperatures inside the high baryon-density phase appears to be robust.