Phase transition between three- and two-flavor QCD?C. Wetterich
Institut für Theoretische Physik, Universität Heidelberg, Philosophenweg 16, 69120 Heidelberg, Germany C.Wetterich@thphys.uni-heidelberg.de
(Received: 12 March 2001 / Revised version: 2 April 2003 / Published online: 2 June 2003)
We explore the possibility that QCD may undergo a phase transition as a function of the strange quark mass. This would hint towards models with "spontaneous color symmetry breaking" in the vacuum. For two light quark flavors 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. The "quark mass phase transition" would be linked to an unusual realization of baryon number in QCD 2 and could be tested in lattice simulations. We emphasize, however, that at the present stage the Higgs picture of the vacuum cannot predict a quark mass phase transition - a smooth crossover remains as a realistic alternative. Implications of the Higgs picture for the high-density phase transition in QCD 2 suggest that this transition is characterized by the spontaneous breaking of isospin for nuclear and quark matter.
© Società Italiana di Fisica, Springer-Verlag 2003