Larkin-Ovchinnikov-Fulde-Ferrell state in two-color quark matter

Abstract

We explore the phase structure of two-color and two-flavor QCD in the space of the quark chemical potential μ_q and the isospin chemical potential μ_I. Using a mean-field model we calculate the chiral and diquark condensates, σand Δ, self-consistently. In weak coupling and in the chiral limit, we confirm the interval of the isospin chemical potential, 0.71Δ_0<μ_I<0.75Δ_0, in which a single plane-wave Larkin-Ovchinnikov-Fulde-Ferrell (LOFF) phase is favored over isotropic superfluidity and normal quark matter. The LOFF window becomes slightly wider at high density. For stronger coupling with nonzero quark mass, which is relevant to currently available numerical simulations in lattice two-color QCD, the single plane-wave LOFF phase appears only at sufficiently high density. The prediction obtained for the LOFF region could be tested with lattice since we can prove that the present system is free from the fermion sign problem. We draw the energy landscape on which local minima corresponding to the isotropic superfluid phase and the LOFF phase and a local maximum corresponding to the gapless phase are manifest. Our results clearly illustrate the path from the the unstable gapless phase down to the LOFF phase.

10 pages, 8 figures

References in corpus (7)

• Deconfinement in dense 2-color QCD
• Chromomagnetic instability in dense quark matter
• The Crystallography of Three-Flavor Quark Matter
• Model study of the sign problem in the mean-field approximation
• Characterizing the Larkin-Ovchinnikov-Fulde-Ferrel phase induced by the chromomagnetic instability
• Instability of a gapless color superconductor with respect to inhomogeneous fluctuations
• Higgs instability in gapless superfluidity/superconductivity

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• Probing the hadron mass spectrum in dense two-color QCD with the linear sigma model
• Chiral effective model of cold and dense two-color QCD: The linear sigma model approach
• Temperature vs. doping phase diagram of cuprate superconductors