Low density instabilities in asymmetric nuclear matter within QMC with $\delta$-meson

TL;DR

This paper investigates the impact of including the $ ext{delta}$-meson in the quark-meson coupling model on the stability and properties of asymmetric nuclear matter, comparing results with and without the $ ext{delta}$-meson.

Contribution

It introduces the $ ext{delta}$-meson into the QMC model and analyzes its effects on nuclear matter stability and symmetry energy, providing new insights into isovector-scalar interactions.

Findings

The $ ext{delta}$-meson modifies the spinodal surfaces and instability regions.

The model with the $ ext{delta}$-meson better matches isospin diffusion constraints.

The distillation effect is affected by the inclusion of the $ ext{delta}$-meson.

Abstract

In the present work we include the isovector-scalar $\delta$-meson in the quark-meson coupling model (QMC) and study the properties of asymmetric nuclear within QMC without and with the $\delta$-meson. Recent constraints set by isospin diffusion on the slope parameter of the nuclear symmetry energy at saturation density are used to adjust the model parameters. The thermodynamical spinodal surfaces are obtained and the instability region at subsaturation densities within QMC and QMC$\delta$ models are compared with mean-field relativistic models. The distillation effect in the QMC model is discussed.