Determination of hadron-quark phase transition line from lattice QCD and two-solar-mass neutron star observations

TL;DR

This paper constructs a hadron-quark phase transition line in the QCD phase diagram using lattice QCD data and neutron star observations, employing a two-phase model with specific effective theories for hadrons and quarks.

Contribution

It introduces a method to determine the hadron-quark transition line by integrating lattice QCD data and neutron star constraints within a two-phase model framework.

Findings

MTEC model aligns best with neutron star data

TM1 model is the second most consistent

The critical baryon chemical potential range for quark matter in neutron stars is identified

Abstract

We aim at drawing the hadron-quark phase transition line in the QCD phase diagram by using the two phase model (TPM) in which the entanglement Polyakov-loop extended Nambu--Jona-Lasinio (EPNJL) model with vector-type four-quark interaction is used for the quark phase and the relativistic mean field (RMF) model is for the hadron phase. Reasonable TPM is constructed by using lattice QCD data and neutron star observations as reliable constraints. For the EPNJL model, we determine the strength of vector-type four-quark interaction at zero quark chemical potential from lattice QCD data on quark number density normalized by its Stefan-Boltzmann limit. For the hadron phase, we consider three RMF models, NL3, TM1 and model proposed by Maruyama, Tatsumi, Endo and Chiba (MTEC). We find that MTEC is most consistent with the neutron star observations and TM1 is the second best. Assuming that the hadron-quark phase transition occurs in the core of neutron star, we explore the density-dependence of vector-type four-quark interaction. Particularly for the critical baryon chemical potential at zero temperature, we determine a range for the quark phase to occur in the core of neutron star.