Nucleons or diquarks: Competition between clustering and color superconductivity in quark matter - art. no. 055209

We study the instabilities of quark matter in the framework of a generalize d Nambu-Jona-Lasinio model, in order to explore possible competition betwee n three-quark clustering to form nucleons and diquark formation leading to color superconductivity; Nucleon and Delta solutions are obtained for the r elativistic Faddeev equation at finite density and their binding energies a re compared with those for the scalar and axial-vector diquarks found from the Bethe-Salpeter equation. In a model with interactions in both scalar an d axial diquark channels, bound nucleons exist up to nuclear matter density . However, except at densities below about a quarter of that of nuclear mat ter, we find that scalar diquark formation is energetically favored. This r aises the question of whether a realistic phase diagram of baryonic matter can be obtained from any model which does not incorporate color confinement .