Strongly Interacting Quark Matter in Massive Quark Stars

This paper investigates the properties of strongly coupled matter at high densities in a quark star (QS). The QS is built from the density-dependent quark mass model (DDQM), modified to obtain higher maximum gravitational mass (M₌₀ₗ) of the QS using the data from observed pulsars: XMMU J173203. 3-344518, PSR J0030+0451, PSR J0740+6620, and PSR J0952-0607 as constraints in Bayesian inference. We observed that the quark matter (QM) that composes QSs with M₌₀ₗ > 2M_ violates the conformality criteria determined through conformal field theory. This behavior is interpreted as a consequence of the increase in quark population with B and the concomitant formation of colored quark and gluon condensates, which are influenced by the pressure build-up in the stellar core as B increases. This is reflected in the enhanced DDQM model employed, which introduces an additional term relevant at high densities. On the other hand, for M₌₀ₗ < 2M_ we observed the desired behavior of the QM as predicted by quantum chromodynamics (QCD) at higher densities, where the interaction decreases with increasing B and eventually the quarks become deconfined due to the depletion of the DDQM through an additional attractive contribution in this case.