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

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-ioncollision 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.

Phase diagrams in nonlocal Polyakov-Nambu-Jona-Lasinio models constrained by lattice QCD results

“…It has been shown that the non-local version of the PNJL model, reproduces hadron properties at zero density and temperature and presents some advantages over the local model [23][24][25]. As another feature, one can add to the model a vector repulsive interaction which increases the stiffness of quark matter and is therefore indispensable to discuss under the observational constraint of 2 M neutron stars [26,27] the possibility of quark matter phases in their interiors [28][29][30][31][32]. Such astrophysical applications have recently also been considered within the nonlocal PNJL model [33][34][35][36].…”

Interface effects of strange quark matter with density dependent quark masses

“…Nevertheless, if the dynamical chiral symmetry breaking is considered, SQM may be unstable [13,14]. In such cases, it can only exist in extreme conditions, e.g., in the centre of compact stars [15][16][17][18][19][20][21] and heavyion collisions [22,23]. The properties of those SQM objects, the structures of SQM inside compact stars, and the processes of quark-hadron transition, are sensitive to the interface effects, where the energy contribution is often taken into account with a surface tension σ.…”

Dynamical generation of a repulsive vector contribution to the quark pressure

“…It is generally believed that effective theories used to describe compressed strongly interacting matter should include vector channels [1][2][3][4][5][6][7][8] such as the ones which appear in the Walecka model for nuclear matter [9] and in the extended version of the Nambu-Jona-Lasinio model (NJL) for quark matter [10]. To emphasize its importance let us point out few recent applications which consider this channel in the framework of the NJL model starting with Ref.…”