Hybrid stars from the NJL model with a tensor interaction

Abstract

In order to obtain the equation of state and construct hybrid stars, we calculate the thermodynamic potential in the two-flavor Nambu-Jona-Lasinio model with tensor-type four-point interaction between quarks. In addition, we impose the β equilibrium and charge neutrality conditions on the system. We show that the tensor condensate appears at large chemical potential, however, it is difficult to hold hybrid stars with two-solar mass by using the equation of state with the tensor interaction. Although we cannot obtain the stars with two-solar mass because of the absence of the repulsive interaction, the estimated magnetic moment density is very large. Therefore, we expect that the tensor interaction describes the magnetic fields of compact stars.

Non-zero tensor condensates in cold quark matter within the three-flavor Nambu-Jona-Lasinio model with the Kobayashi-Maskawa-'t Hooft interaction

“…Further, the implication to the compact stars such as neutron stars and magnetars should be investigated by assuming the existence of the tensor condensates, related to the light quarks and the strange quark, while we have investigated the effect of the tensor condensate on the radius-mass relation of the hybrid quark star in the two-flavor case. 30) This may be interesting future problem.…”

“…29) In this paper, we concentrate on the spin polarization due to the tensor condensate originated from the tensor interaction between quarks in an extended NJL model. In our previous paper in 19), 20), 30), the spin polarization due to the tensor condensate has been investigated widely in the case of the two-flavor NJL model. In this paper, we extend our previous work to the case of three-flavor NJL model.…”

Spin polarizations under a pseudovector interaction between quarks with the Kobayashi–Maskawa–’t Hooft term in high density quark matter

“…These are interesting future problems which are left in order to clarify the magnetic properties of high density quark matter. Further, the implication to the compact stars such as the neutron star and magnetar should be investigated 31) by assuming the existence of the pseudovector condensate related to the light quarks and the strange quark. This may be interesting future problem.…”

Hybrid stars from a three-flavor NJL model with two kinds of tensor condensates

“…In a previous paper [25] and in our recent paper [26], the spin polarization due to the tensor condensate has been investigated in the case of the three-flavor NJL model with the Kobayashi-Maskawa-'t Hooft interaction. [34,35] Also, properties of the compact star is investigated in the case of the two-flavor NJL model with tensor interaction [36]. Thus, the investigation of the compact stars with the three-flavor quark matter in the inner core of the compact stars such as hybrid stars is left.…”