Effects of Hadron-Quark Phase Transitions in Hybrid Stars within the NJL Model

Abstract

We study local and non-local Polyakov Nambu-Jona-Lasinio models and analyze their respective phase transition diagram. We construct hybrid stars using the zero temperature limit of the local and non-local versions of Nambu-Jona-Lasinio model for quark matter and the modern GM1(L) parametrization of the non-linear relativistic mean field model for hadronic matter. We compare our models with data from PSR J1614-2230 and PSR J0343+0432 and also from GW170817 and its electromagnetic counterpart GRB170817A and AT2017gfo. We study observational signatures of the appearance of a mixed phase as a result of modeling a phase transition that mimics the Gibbs formalism and compare the results with the sharp first-order phase transition obtained using the Maxwell construction. We also study in detail the g-mode associated with discontinuities in the equation of state, and calculate non-radial oscillation modes using relativistic Cowling approximation.

Strong-Interaction Matter under Extreme Conditions from Chiral Quark Models with Nonlocal Separable Interactions

“…Moreover, it is argued that GW170817 data also imply a general upper limit of about 2.3M for the mass of a cold spherical NS [221]. These constraints have been taken into account for the analysis of EoS arising from hybrid star models that include nlNJL approaches for quark matter [222][223][224][225][226][227][228].…”

“…In Refs. [223,225], these new constraints are considered in the context of the above described three-flavor nonlocal NJL models, at both zero and finite temperature. In the finite temperature region, the treatment of quark matter includes the coupling between the quarks and the Polyakov loop, as described in Section 2.2.…”

“…In addition, new parameterizations called DD2 and GM1L are used for the description of the purely hadronic phase. They are based on the standard relativistic mean field approach, taking into account medium effects through the inclusion of explicit density dependent meson-baryon couplings [223,229]. The hadron-quark transition is treated according to a Maxwell construction in which there is a sharp interface and no mixed phase regions.…”

Hadron–Quark Phase Transition in the SU (3) Local Nambu–Jona-Lasinio (NJL) Model with Vector Interaction

“…This model successfully reproduces many features of quantum chromodynamics (QCD) [37][38][39][40][41]. By combining various modifications of the NJL quark model with different models for describing hadronic matter, the authors of a number of works have constructed a hybrid equation of state and, on their basis, have investigated the properties of neutron stars containing deconfined quark matter (see, e.g., [42][43][44][45][46][47][48][49][50][51][52]). Several approaches for studying the properties of both quark matter and hadronic matter and, on their basis, elucidating the features of the quark-hadron phase transition can be found in the topical issue [53].…”

Hadron-Quark Phase Transition in the SU(3) Local Nambu – Jona-Lasinio (NJL) Model with Vector Interaction

“…This model successfully reproduces many features of quantum chromodynamics (QCD) [34][35][36][37][38]. By combining various modifications of the NJL quark model with different models for describing hadronic matter, the authors of a number of works have constructed a hybrid equation of state and, on their basis, have investigated the properties of neutron stars containing deconfined quark matter (see, e.g., [39][40][41][42][43][44][45][46][47]).…”