Instabilities of relativistic mean field models and the role of nonlinear terms

TL;DR

This paper investigates the stability issues of relativistic mean field models in nuclear physics, highlighting how nonlinear terms influence the stability of particle-hole excitation modes and suggesting ways to improve model reliability at high densities.

Contribution

It demonstrates the impact of nonlinear vector and scalar terms on the stability of RMF models and shows how these can mitigate instabilities in high-density applications.

Findings

Nonlinear terms significantly affect mode stability.

Certain parameter sets can be stabilized with nonlinear terms.

Some RMF models remain unstable at high densities.

Abstract

The instability of nuclear matter due to particle-hole excitation modes has been studied in the frame-work of several relativistic mean field (RMF) models. It is found that both the longitudinal and the transversal modes depend sensitively on the parameter sets used. The important impact of the vector and vector-scalar nonlinear terms on the stability of both modes is demonstrated. Our finding corroborates the result of previous studies, namely that certain RMF models cannot be used in high density applications. However, we show that for certain parameter sets of RMF models this shortcoming can be alleviated by adding these nonlinear terms.