Excluded volume and isospin in dense quark matter: effects on the properties of hybrid stars.
A systematic study of hybrid stars composed of quarks and hadrons was conducted using an equation of state for quark matter based on the QMDDM (quark-mass density-dependent model). In this model, quarks are treated as quasi-particles whose mass depends on the properties of the medium. The main advancement of this work is the extension of the QMDDM to include isospin dependence in the effective mass of quarks, as well as the effect of excluded volume due to repulsive interactions between quarks. The impact of these modifications on some global properties of hybrid stars, such as the mass-radius relation and tidal deformabilities, was analyzed. The theoretical predictions of the model were compared with the results of recent astrophysical observations, including the GW170817 gravitational wave event, associated with the merger of two neutron stars, and recent pulsar measurements.