Hybrid stars from the NJL model with a tensor interaction

TL;DR

This paper investigates the impact of tensor interactions in the NJL model on the equation of state for hybrid stars, finding that while tensor condensates form at high densities, they do not support two-solar-mass stars but suggest a role in magnetic field generation.

Contribution

It introduces the inclusion of tensor-type four-point interactions in the NJL model for hybrid star modeling, highlighting their effects on the equation of state and magnetic properties.

Findings

Tensor condensate appears at high chemical potential.

Hybrid stars with tensor interactions cannot reach two-solar-mass.

Large magnetic moment density suggests a role in magnetic field generation.

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 beta 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 absense of the repulsive interaction, the estimated magnetic moment density is very large. Therefore, we expect that the tensor interaction descrobes the magnetic fields of compact stars.