On the Study of Symmetry Energy of Quark Matter and Tidal Deformability of Quark Stars

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.