Philip D. Powell, Gordon Baym
We investigate the effects of confinement and local color neutrality on quark pairing at intermediate chemical potentials in the three flavor Nambu--Jona-Lasinio model with Polyakov loop. While prior studies have indicated the presence of a color-flavor-locked (CFL) phase at low temperatures and intermediate to high chemical potentials, we find that in the absence of a local color neutrality constraint the inclusion of the Polyakov loop gives rise to a new preferred phase in which all quark colors and flavors pair, but with unequal magnitudes. We study this asymmetric color-flavor-locked (ACFL) phase, which exists even for equal mass quarks, by identifying its location in the phase diagram, the order of the associated phase transitions, and its symmetry breaking pattern, which proves to be the intersection of the symmetry groups of the 2SC and CFL phases. We also investigate the effects of the strange quark mass on this new phase and the QCD phase diagram generally. Finally, we analyze the effect of a local color neutrality constraint on the QCD phase diagram and observe that under at least certain conditions it eliminates both the 2SC and ACFL phases by rendering them energetically unfavorable. Thus, we observe the previously proposed low temperature critical point emerge with the associated continuity between hadronic and color superconducting quark matter.
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http://arxiv.org/abs/1302.0416
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