Mixed phases of compact star matter in a unified mean-field approach

TL;DR

This paper uses an extended NJL model to study mixed phases in dense stellar matter, revealing geometric structures during phase transitions and their implications for understanding compact star cores.

Contribution

It introduces a unified mean-field approach to analyze various first-order phase transitions in dense matter, incorporating complex geometries and interactions.

Findings

Geometrical structures appear in liquid-gas and deconfinement transitions.

No geometrical structures are found for chiral phase transitions.

Attractive interactions between strange quark matter and hyperons are observed.

Abstract

Based on an extended NJL model that treats baryons as clusters of quarks, we investigate the properties and microscopic structures of mixed phases for various types of first-order phase transitions in a unified manner, where the model parameters are fixed by reproducing nuclear matter properties and the binding energies of finite nuclei. In particular, based on the Thomas-Fermi approximation, we investigate the mixed phases arise from the liquid-gas phase transition of nuclear matter, chiral phase transition, and deconfinement phase transition in dense stellar matter adopting spherical and cylindrical approximations for the Wigner-Seitz cells. It is found that the geometrical structures do not emerge for chiral phases transition, while the droplet, rod, slab, tube, and bubble phases emerge sequentially as density increases for the liquid-gas and deconfinement phase transitions. Additional attractive interactions between strange quark matter and hyperons are observed as the deconfinement phase transition is entangled with chiral phase transition of $s$ quarks. The results obtained here should be useful to understand the properties and structures of dense stellar matter throughout compact stars and in particular the matter state in the core regions. Meanwhile, more extensive investigations in a three-dimensional geometry with large box sizes are necessary for our future study.