Phase diagram of chiral quark matter: Fulde-Ferrell pairing from weak to strong coupling - Nuclear TheoryReport as inadecuate




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Abstract: We calculate the phase diagram of two-flavor quark matter in thetemperature-flavor asymmetry plane in the case where there are three competingphases: the homogeneous Bardeen-Cooper-Schrieffer BCS phase, the unpairedphase, and a phase with broken spatial symmetry, which is here taken to be thecounterpart of the Fulde-Ferrell FF phase in condensed matter physics. Weshow that the system belongs to the universality class ofparamagnetic-ferromagnetic -helical systems. We vary the coupling constant ofthe theory, which is obtained from integrating out the gluonic degrees offreedom. In weak coupling, the FF phase is favored at arbitrary flavorasymmetries for sufficiently low temperatures; at intermediate coupling itsoccupancy domain is shifted towards larger asymmetries. Strong couplingfeatures a new regime of an inhomogeneous FF state, which we identify with acurrent-carrying Bose-Einstein condensate of tightly bound up and down quarks.We analyze the occupation numbers and the Cooper-pair wave function and showthat when the condensate momentum is orthogonal to the particle momentum theminority component contains a blocking region breach around the Fermi spherein the weak-coupling limit, which engulfs more low-momentum modes as thecoupling is increased, and eventually leads to a topological change in strongcoupling, where the minority Fermi sphere contains either two occupied stripsor an empty sphere. For non-orthogonal momenta, the blocking region is eitherreduced or extinct, i.e., no topological changes are observed.



Author: Armen Sedrakian, Dirk H. Rischke

Source: https://arxiv.org/







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