Quark deconfinement in compact stars through sexaquark condensation

Abstract

In this contribution, we present for the first time a scenario according to which early quark deconfinement in compact stars is triggered by the Bose-Einstein condensation (BEC) of a light sexaquark (S) with a mass $m_S<2054$ MeV, that has been suggested as a candidate particle to explain the baryonic dark matter in the Universe. The onset of S BEC marks the maximum mass of hadronic neutron stars and it occurs when the condition for the baryon chemical potential $\mu_b=m_S/2$ is fulfilled in the center of the star, corresponding to $M_{\rm onset}\lesssim 0.7~M_\odot$. In the gravitational field of the star the density of the BEC of the S increases until a new state of the matter is attained, where each of the S-states got dissociated into a triplet of color-flavor-locked (CFL) diquark states. These diquarks are the Cooper pairs in the color superconducting CFL phase of quark matter, so that the developed scenario corresponds to a BEC-BCS transition in strongly interacting matter. For the description of the CFL phase, we develop here for the first time the three-flavor extension of the density-functional formulation of a chirally symmetric Lagrangian model of quark matter where confining properties are encoded in a divergence of the scalar self-energy at low densities and temperatures.