Deconfined, massive quark phase at high density and compact stars: A holographic study
Kazem Bitaghsir Fadafan, Jesús Cruz Rojas, Nick Evans
Abstract
In Hoyos et al. [Phys. Rev. Lett. 117, 032501 (2016)], a holographic $\mathrm{D}3/\mathrm{D}7$ system was used to describe a deconfined yet massive quark phase of QCD at finite density, concluding that the equation of state of such a phase was not stiff enough to support exotic dense stars. That analysis used a hard quark mass to represent the dynamical mass and assumed a conformal gauge background. Here, we phenomenologically adjust the $\mathrm{D}3/\mathrm{D}7$ system to include a running anomalous dimension for the quark condensate. This introduces a dynamical mechanism for chiral symmetry breaking, yet the model still has a deconfined massive phase at intermediate densities. We show that these systems, dependent on the running profile in the deep IR, generate much stiffer equations of state and nonmonotonic behavior in the speed of sound. The results suggest that these equations of state may be closer to supporting hybrid stars with quark cores.