Heavy hybrid stars from multi-quark interactions

We explore the possibility of obtaining heavy hybrid stars within the framework of the two flavor Nambu--Jona-Lasinio model with 8-quark interactions in the scalar and in the vector channel. The main impact of the 8-quark scalar channel is to reduce the onset of quark matter, while the 8-quark vector channel acts to stiff the equation of state at high densities. Within the parameter space where the 4-quark vector channel is small, and the 8-quark vector channel sizeable, stable stars with $2 M_\odot$ and above are found to hold quark matter in their cores.