Phase transition between three- and two-flavor QCD?

Spontaneous breaking of color is investigated for the vacuum of QCD$_2$ with two light flavors of quarks. We classify possible colored quark-antiquark, diquark and gluon condensates that are compatible with a spectrum of integer charged states and conserved isospin and baryon number. An unusual realization of baryon number in QCD$_2$ suggests that there may be a phase transition between two- and three-flavor QCD as a function of the strange quark mass. This could be seen in lattice simulations. We also discuss the qualitative features of the high density phase transition in QCD$_2$ and suggest the spontaneous breaking of isospin for nuclear and quark matter. We finally remark that spontaneous breaking of color may also occur in pure QCD without quarks