Bound diquarks and their Bose-Einstein condensation in strongly coupled quark matter

We explore the formation of diquark molecules and their Bose-Einstein condensation (BEC) in the phase diagram of three-flavor quark matter at nonzero temperature, T, and quark chemical potential, mu. Using a quark model with a four-fermion interaction, we identify possible diquark excitations as poles of the microscopically computed diquark propagator. The quark masses are obtained by solving a dynamical equation for the chiral condensate and are found to determine the stability of the diquark excitations. The stability of diquark excitations is investigated in the T-mu plane for different values of the diquark coupling strength. We find that bound diquark molecules appear at small quark chemical potentials at intermediate coupling and that BEC of non-strange diquark molecules occurs if the attractive interaction between quarks is sufficiently strong.