Quark matter in an SU(3) Nambu–Jona-Lasinio model with two types of vector interactions

We investigate the properties of asymmetric quark matter and strange quark matter in the framework of the SU(3) Nambu–Jona-Lasinio (NJL) model with two types of vector interactions: (1) the flavor-dependent repulsion among different flavors of quarks with the coupling constant $G_V$, and (2) the universal repulsion and the vector-isovector interaction among different flavors of quarks with the coupling constants $g_V$ and $G_{IV}$. Using these two types of vector interactions in the NJL model, we study the quark symmetry energy in asymmetric quark matter, the constituent quark mass, the quark fraction, the equation of state in strange quark matter, the maximum mass of a quark star, and the properties of the QCD phase diagram. We find that including the two types of vector interactions in the SU(3) NJL model can significantly influence the quark matter symmetry energy as well as the properties of strange quark matter and quark stars. In particular, our results indicate that we can describe PSR $\mathrm{J}1614-2230$ and PSR $\mathrm{J}0348+0432$ as quark stars by considering the universal repulsion and the vector-isovector interaction among quark matter in the SU(3) NJL model.

Figure 1

Quark matter symmetry energy within different vector interactions from the NJL model.

Figure 2

Constituent mass for $u$, $d$, and $s$ quarks as functions of baryon density in SQM within different vector interactions.

Figure 3

Quark fraction as a function of the baryon density in SQM within the NJL model with different vector interactions.

Figure 4

Pressure as a function of energy density for SQM within different vector interactions.

Figure 5

The maximum mass of quark stars from the SU(3) NJL model by varying $g_V$ and $G_{IV}$.

Figure 6

Phase diagram in the $\mu \text{−}T$ plane with different vector interactions in asymmetric quark matter within the SU(3) NJL model.