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The Phase Diagram of the Quark-Meson Model

Bernd-Jochen Schaefer·Jochen Wambach
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Abstract

Within the proper-time renormalization group approach, the chiral phase diagram of a two-flavor quark-meson model is studied. In the chiral limit, the location of the tricritical point which is linked to a Gaussian fixed point, is determined. For quark chemical potentials smaller than the tricritical one the second-order phase transition belongs to the O(4) universality class. For temperatures below the tricritical one we find initially a weak first-order phase transition which is commonly seen in model studies and also in recent lattice simulations. In addition, below temperatures of T <~ 17 MeV we find two phase transitions. The chiral restoration transition is initially also of first-order but turns into a second-order transition again. This leads to the possibility that there may be a "second tricritical" point in the QCD phase diagram in the chiral limit.

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Bernd-Jochen Schaefer, Jochen Wambach. 2005-04-12. The Phase Diagram of the Quark-Meson Model. https://doi.org/10.1016/j.nuclphysa.2005.04.012

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