Holographic quark matter with color superconductivity and a stiff equation of state for compact stars
Kazem Bitaghsir Fadafan, Jesús Cruz Rojas, Nick Evans
Abstract
We present a holographic model of QCD with a first order chiral restoration phase transition with chemical potential, $\ensuremath{\mu}$. The first order behavior follows from allowing a discontinuity in the dual description as the quarks are integrated out below their constituent mass. The model predicts a deconfined yet massive quark phase at intermediate densities ($350\text{ }\text{ }\mathrm{MeV}<\ensuremath{\mu}<500\text{ }\text{ }\mathrm{MeV}$), above the nuclear density phase, which has a very stiff equation of state and a speed of sound close to one. We also include a holographic description of a color superconducting condensate in the chirally restored vacuum and study the resulting equation of state. They provides a well behaved first order transition from the deconfined massive quark phase at very high density ($\ensuremath{\mu}>500\text{ }\text{ }\mathrm{MeV}$). We solve the Tolman-Oppenheimer-Volkoff equations with the resulting equations of state and find stable hybrid stars with quark cores. We compute the tidal deformability for these hybrid stars and show they are consistent with LIGO/Virgo data on a neutron star collision. Our holographic model shows that quark matter could be present at the core of such compact stars.