121705206
Reply to “Comment on ‘Interaction induced deformation of the momentum distribution of spin polarized nuclear matter’ ”
A comparison is made between a Brueckner-Hartree-Fock study of spin polarized nuclear matter allowing for deformation of the Fermi spheres and studies of such systems in terms of the Landau parametrization of the effective interaction.
119116866
Phase diagram of chiral quark matter: Fulde-Ferrell pairing from weak to strong coupling
We calculate the phase diagram of two-flavor quark matter in the temperature-flavor asymmetry plane in the case where there are three competing phases: the homogeneous Bardeen-CooperSchrieffer (BCS) phase, the unpaired phase, and a phase with broken spatial symmetry, which is here taken to be the counterpart of the Fulde-Ferrell (FF) phase in condensed matter physics. The system belongs to the universality class of paramagnetic-ferromagnetic-helical systems, and therefore contains a tricritical Lifshitz point in its phase diagram, where the momentum scale characterizing the breaking of translational invariance has a critical exponent of 1/2 to leading order. We vary the coupling constant of the theory, which is obtained from integrating out the gluonic degrees of freedom. In weak coupling, the FF phase is favored at arbitrary flavor asymmetries for sufficiently low temperatures; at intermediate coupling its occupancy domain is shifted towards larger asymmetries. Strong coupling features a new regime of an inhomogeneous FF state, which we identify with a current-carrying Bose-Einstein condensate of tightly bound up and down quarks. The temperature and asymmetry dependence of the gap function is studied. It is shown that the anomalous temperature dependence of the gap in the homogeneous, flavor-asymmetric phase is transformed into a normal dependence (self-similar to the BCS phase) at arbitrary coupling, once the FF phase is allowed for. We analyze the occupation numbers and the Cooper-pair wave function and show that when the condensate momentum is orthogonal to the particle momentum the minority component contains a blocking region (breach) around the Fermi sphere in the weak-coupling limit, which engulfs more low-momentum modes as the coupling is increased, and eventually leads to a topological change in strong coupling, where the minority Fermi sphere contains either two occupied strips or an empty sphere. For non-orthogonal momenta, the blocking region is either reduced or extinct, i.e., no topological changes are observed.
54713615
Composition and stability of hybrid stars with hyperons and quark color-superconductivity
The recent measurement of a 1.97 ± 0.04 solar-mass pulsar places a stringent lower bound on the maximum mass of compact stars and therefore challenges the existence of any agents that soften the equation of state of ultra-dense matter. We investigate whether hyperons and/or quark matter can be accommodated in massive compact stars by constructing an equation of state based on a combination of phenomenological relativistic hyper-nuclear density functional and an effective model of quantum chromodynamics (the
118545262
Phase diagram of chiral quark matter: Color and electrically neutral Fulde-Ferrell phase
The phase diagram of charge and color neutral two-flavor color superconducting quark matter is studied including the homogeneous two-flavor superconductor (2SC) and the inhomogeneous Fulde-Ferrell (FF) phases within the Nambu-Jona-Lasinio model. The low-temperature domain T{<=}5 MeV of the phase diagram contains the FF phase, which borders at high temperatures to the 2SC phase. The critical temperature of phase transition from the 2SC to the unpaired state is in the range 20-30 MeV. We derive the equation of state of matter and its composition and show that matter in mature compact stars should be in the inhomogeneous FF-like superconducting state. We briefly discuss the astrophysical implications of such a phase in compact stars.
32060667
Pairing in a two-component ultracold Fermi gas: Phases with broken-space symmetries
We explore the phase diagram of a two-component ultracold atomic Fermi gas interacting with zero-range forces in the limit of weak coupling. We focus on the dependence of the pairing gap and the free energy on the variations in the number densities of the two species while the total density of the system is held fixed. As the density asymmetry is increased, the system exhibits a transition from a homogenous Bardeen-Cooper-Schrieffer (BCS) phase to phases with spontaneously broken global space symmetries. One such realization is the deformed Fermi surface superfluidity (DFS) which exploits the possibility of deforming the Fermi surfaces of the species into ellipsoidal form at zero total momentum of Cooper pairs. The critical asymmetries at which the transition from DFS to the unpaired state occurs are larger than those for the BCS phase. In this precritical region the DFS phase lowers the pairing energy of the asymmetric BCS state. We compare quantitatively the DFS phase to another realization of superconducting phases with broken translational symmetry: the single-plane-wave Larkin-Ovchinnikov-Fulde-Ferrell phase, which is characterized by a nonvanishing center-of-mass momentum of the Cooper pairs. The possibility of the detection of the DFS phase in the time-of-flight experiments is discussed and quantified for the case of Li-6 atoms trapped in two different hyperfine states.
118895506
From integrable models to gauge theories : a volume in honor of Sergei Matinyan
3D Ising model on dual BCC lattice - the sign-factor, J. Ambjorn et al on algebra of the Baxter Q-operators, A.A. Belavin and R.A. Usmanov aspect of locality in the form factor programme, O.A. Castro-Alvaredo and A. Fring on the origin of symmetries, J.L. Chkareuli generalization of magnetic fields in cosmology, A.D. Dolgov the coefficients of the Seiberg-Witten prepotential as interaction numbers, R. Flume et al on the cosmological constant and vacuum energy, V.G. Gurzadyan and S.S. Xue topics in Parton model, O.V. Kancheli Bjorken asymptotics of QCD and integrable systems, D. Karakhanyan and R. Kirschner entropy and area of black holes in loop quantum gravity, I.B. Khriplovich statistical ensembles and density of states, V. Kostrykin and R. Schrader the anthropic principle revisited, B. Mueller fundamental units, L.B. Okun structure constant of boundary operators in Liouville field theory, B. Ponsot and J. Teschner winding number versus Chern-Pontryagin charge, T. Tchrakian magnetically induced vacuum-energy releasing, S.S. Xue. (Part contents)