Density functional theory of renormalization group in nuclear matter

TL;DR

This paper introduces a density functional renormalization group approach to study high-density nuclear matter, revealing medium effects on nucleon interactions and discovering a Fermi surface locking phenomenon.

Contribution

It develops a novel density functional RG method applied to the Walecka model, providing new insights into nuclear matter properties at high densities.

Findings

Screening of nucleon-meson interactions at high densities

Stiffer EoS for densities up to 2.5 times saturation density

Discovery of Fermi surface locking phenomenon

Abstract

The density functional renormalization group (density-fRG) is proposed to investigate the density fluctuations within the functional renormalization group approach, which allows us to quantify the medium effect and study physics of high densities. This method is applied to the nucleon-meson effective field theory, also known as the Walecka model, to study the properties of nuclear matter at high baryon densities. It is found that both the attractive and repulsive nucleon meson interactions are screened by the high density medium, which results in a stiffer equation of state (EoS) of nuclear matter in the regime of $\rho_0 \lesssim \rho \lesssim 2.5 \rho_0$, then a softer EoS when $\rho \gtrsim 2.5 \rho_0$. Here $\rho_0$ denotes the saturation baryon density of symmetric nuclear matter. Furthermore, a new phenomenon called the locking of Fermi surface is found. In the locking of Fermi surface the effective energy of quasi-nucleon is always close to the Fermi surface, which are both running with the renormalization group scale.