Abstract:
Research performed during the past decade revealed an important role of symmetry energy in the equation of state of quark matter. By introducing an isospin-dependent term into the quark mass scaling, the stability window of quark matter was studied in the equivparticle model. The results show that a sufficiently strong isospin dependence C_I can significantly widen the absolute stable region of strange quark matter, yielding results that simultaneously satisfy the constraints of the astrophysical observations of PSR J1614-2230 with (1.928 ± 0.017) M_\odot and tidal deformability 70 \leqslant \varLambda_1.4 \leqslant 580 measured in the event GW170817. Contrary to the case of strange quark matter, the stable region of u-d quark matter narrows with isospin dependence C_I , leading to inconsistency with astrophysical observations. Finally, we found that the symmetry energy of strange quark matter is much larger than that of u-d quark matter, and one-gluon exchange interaction between quarks causes the symmetry energy of strange quark matter to become softer.