Quark matter in light neutron stars

Understand

Higher-order repulsive interactions are included in the three-flavor NJL model in order to describe the quark phase of an hybrid star.

• The effect of 4-quark and 8-quark vector-isoscalar interactions in the stability of hybrid star configurations is analyzed.
• The presence of a 8-quark vector-isoscalar channel is seen to be crucial in generating large quark branches in the $M(R)$ diagram.
• This is due to its stiffening effect on the quark matter equation of state which arises from the non-linear density dependence of the speed of sound.