Chirally improved quark Pauli blocking in nuclear matter and applications to quark deconfinement in neutron stars

TL;DR

This paper modifies the relativistic mean field model of nuclear matter by incorporating quark Pauli blocking effects with chiral enhancement, exploring implications for quark deconfinement and high-mass twin stars in neutron stars.

Contribution

It introduces a density-dependent scheme for quark Pauli blocking within the RMF model and applies it to neutron star matter, including phase transition and star sequence analysis.

Findings

Quark Pauli blocking significantly affects the nuclear equation of state.

The model predicts high-mass twin compact star solutions.

The density-dependent symmetry energy aligns with phenomenological constraints.

Abstract

The relativistic mean field (RMF) model of the nuclear matter equation of state has been modified by including the effect of Pauli-blocking owing to quark exchange between the baryons. Different schemes of a chiral enhancement of the quark Pauli blocking have been suggested according to the adopted density dependence of the dynamical quark mass. The resulting equations of state for the pressure are compared to the RMF model DD2 with excluded volume correction. On the basis of this comparison a density-dependent nucleon volume is extracted which parametrises the quark Pauli blocking effect in the respective scheme of chiral enhancement. The dependence on the isospin asymmetry is investigated and the corresponding density dependent nuclear symmetry energy is obtained in fair accordance with phenomenological constraints. The deconfinement phase transition is obtained by a Maxwell construction with a quark matter phase described within a higher order NJL model. Solutions for rotating and nonrotating (hybrid) compact star sequences are obtained which show the effect of high-mass twin compact star solutions for the rotating case.