Fluctuations in the quark-meson model for QCD with isospin chemical potential |
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Authors: | Kazuhiko Kamikado Nils Strodthoff Lorenz von Smekal Jochen Wambach |
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Institution: | 1. Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502, Japan;2. Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany;3. GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt, Germany |
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Abstract: | We study the two-flavor quark-meson (QM) model with the functional renormalization group (FRG) to describe the effects of collective mesonic fluctuations on the phase diagram of QCD at finite baryon and isospin chemical potentials, μB and μI. With only isospin chemical potential there is a precise equivalence between the competing dynamics of chiral versus pion condensation and that of collective mesonic and baryonic fluctuations in the quark-meson-diquark model for two-color QCD at finite baryon chemical potential. Here, finite μB=3μ introduces an additional dimension to the phase diagram as compared to two-color QCD, however. At zero temperature, the (μI,μ) plane of this phase diagram is strongly constrained by the “Silver Blaze problem.” In particular, the onset of pion condensation must occur at μI=mπ/2, independent of μ as long as μ+μI stays below the constituent quark mass of the QM model or the liquid-gas transition line of nuclear matter in QCD. In order to maintain this relation beyond mean field it is crucial to compute the pion mass from its timelike correlator with the FRG in a consistent way. |
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Keywords: | QCD phase diagram Isospin density Functional renormalization group |
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