The onset and deconfinement transitions in two-colour QCD

Abstract

We study two-colour QCD with two flavours of Wilson fermion at non-zero chemical potential mu and zero temperature. We find evidence of two separate transitions: an onset transition at mu ~ m_pi/2 where quark number and energy densities increase from zero; and a deconfinement transition at higher mu. The mu-dependence of the number and energy densities and the diquark condensate indicate that a Fermi surface is formed and that BCS rather than Bose-Einstein condensation dominates at the quark mass considered here, especially beyond the deconfinement transition.