Isoscalar-vector interaction and hybrid quark core in massive neutron stars

TL;DR

This paper investigates the role of isoscalar-vector interactions in the quark matter core of massive neutron stars using a two-phase model, highlighting its importance for star properties and potential signals in heavy-ion collisions.

Contribution

It introduces an isoscalar-vector interaction in the quark matter model and demonstrates its critical influence on the hadron-quark phase transition and neutron star characteristics.

Findings

Isoscalar-vector interaction is essential for the existence of massive hybrid stars.

The interaction strength affects the quark matter onset density and star mass-radius relations.

Implications for heavy-ion collision signals of the hadron-quark phase transition.

Abstract

The hadron-quark phase transition in the core of massive neutron stars is studied with a newly constructed two-phase model. For nuclear matter, a nonlinear Walecka type model with general nucleon-meson and meson-meson couplings, recently calibrated by Steiner, Hemper and Fischer, is taken. For quark matter, a modified Polyakov-Nambu--Jona-Lasinio (mPNJL) model, which gives consistent results with lattice QCD data, is used. Most importantly, we introduce an isoscalar-vector interaction in the description of quark matter, and we study its influence on the hadron-quark phase transition in the interior of massive neutron stars. With the constraints of neutron star observations, our calculation shows that the isoscalar-vector interaction between quarks is indispensable if massive hybrids star exist in the universe, and its strength determines the onset density of quark matter, as well as the mass-radius relations of hybrid stars. Furthermore, as a connection with heavy-ion-collision experiments we give some discussions about the strength of isoscalar-vector interaction and its effect on the signals of hadron-quark phase transition in heavy-ion collisions, in the energy range of the NICA at JINR-Dubna and FAIR at GSI-Darmstadt facilities.