9,778 research outputs found

    Coupled SDW and Superconducting Order in FFLO State of CeCoIn5_5

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    The mechanism of incommensurate (IC) spin-density-wave (SDW) order observed in the Flude-Ferrell-Larkin-Ovchinnikov (FFLO) phase of CeCoIn5_5 is discussed on the basis of new mode-coupling scheme among IC-SDW order, two superconducting orders of FFLO with B1g_{1{\rm g}} (dx2−y2d_{x^{2}-y^{2}}) symmetry and π\pi-pairing of odd-parity. Unlike the mode-coupling schemes proposed by Kenzelmann et al, Sciencexpress, 21 August (2008), that proposed in the present Letter can offer a simple explanation for why the IC-SDW order is observed only in FFLO phase and the IC wave vector is rather robust against the magnetic field.Comment: 3pages, 1 figure, accepted for publication in J. Phys. Soc. Jpn., Vol.77 (2008), No.1

    Neural Relax

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    We present an algorithm for data preprocessing of an associative memory inspired to an electrostatic problem that turns out to have intimate relations with information maximization

    Non-minimal Einstein-Yang-Mills-Higgs theory: Associated, color and color-acoustic metrics for the Wu-Yang monopole model

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    We discuss a non-minimal Einstein-Yang-Mills-Higgs model with uniaxial anisotropy in the group space associated with the Higgs field. We apply this theory to the problem of propagation of color and color-acoustic waves in the gravitational background related to the non-minimal regular Wu-Yang monopole.Comment: 14 pages, no figure

    Role of Light Vector Mesons in the Heavy Particle Chiral Lagrangian

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    We give the general framework for adding "light" vector particles to the heavy hadron effective chiral Lagrangian. This has strong motivations both from the phenomenological and aesthetic standpoints. An application to the already observed D \rightarrow \overbar{K^*} weak transition amplitude is discussed.Comment: 19 pages, LaTeX documen

    One-loop flavor changing electromagnetic transitions

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    We discuss the effect of the external fermion masses in the flavor-changing radiative transitions of a heavy fermion (quark or lepton) to a lighter fermion at the one-loop level, and point out an often overlooked crucial difference in the sign of a charge factor between transitions of the down type s→dγs\to d\gamma and the up type c→uγc\to u\gamma. We give formulas for the F→fγF\to f\gamma effective vertex in various approximations and the exact formula for t→cγt\to c\gamma and τ→μγ\tau \to \mu \gamma.Comment: LaTeX 16 pages + 4 postscript figures. Misprints corrected, some Comments adde

    Tricritical Phenomena at the Cerium γ→α\gamma \to \alpha Transition

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    The γ→α\gamma \to \alpha isostructural transition in the Ce0.9−x_{0.9-x}Lax_xTh0.1_{0.1} system is measured as a function of La alloying using specific heat, magnetic susceptibility, resistivity, thermal expansivity/striction measurements. A line of discontinuous transitions, as indicated by the change in volume, decreases exponentially from 118 K to close to zero with increasing La doping and the transition changes from being first-order to continuous at a critical concentration 0.10≤xc≤0.140.10 \leq x_c \leq 0.14. At the tricritical point, the coefficient of the linear TT term in the specific heat γ\gamma and the magnetic susceptibility start to increase rapidly near xx = 0.14 and gradually approaches large values at xx=0.35 signifying that a heavy Fermi-liquid state evolves at large doping. Near xcx_c, the Wilson ratio, RWR_W, has a value of 3.0, signifying the presence of magnetic fluctuations. Also, the low-temperature resistivity shows that the character of the low-temperature Fermi-liquid is changing

    Off-shell effects in dilepton production from hot interacting mesons

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    The production of dielectrons in reactions involving a_1 mesons and pions is studied. We compare results obtained with different phenomenological Lagrangians that have been used in connection with hadronic matter and finite nuclei. We insist on the necessity for those interactions to satisfy known empirical properties of the strong interaction. Large off-shell effects in dielectron production are found and some consequences for the interpretation of heavy ion data are outlined. We also compare with results obtained using experimentally-extracted spectral functions.Comment: 14 pages, LaTeX2e, 2 figure

    Light Rays at Optical Black Holes in Moving Media

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    Light experiences a non-uniformly moving medium as an effective gravitational field, endowed with an effective metric tensor g~μν=ημν+(n2−1)uμuν\tilde{g}^{\mu \nu}=\eta^{\mu \nu}+(n^2-1)u^\mu u^\nu, nn being the refractive index and uμu^\mu the four-velocity of the medium. Leonhardt and Piwnicki [Phys. Rev. A {\bf 60}, 4301 (1999)] argued that a flowing dielectric fluid of this kind can be used to generate an 'optical black hole'. In the Leonhardt-Piwnicki model, only a vortex flow was considered. It was later pointed out by Visser [Phys. Rev. Lett. {\bf 85}, 5252 (2000)] that in order to form a proper optical black hole containing an event horizon, it becomes necessary to add an inward radial velocity component to the vortex flow. In the present paper we undertake this task: we consider a full spiral flow, consisting of a vortex component plus a radially infalling component. Light propagates in such a dielectric medium in a way similar to that occurring around a rotating black hole. We calculate, and show graphically, the effective potential versus the radial distance from the vortex singularity, and show that the spiral flow can always capture light in both a positive, and a negative, inverse impact parameter interval. The existence of a genuine event horizon is found to depend on the strength of the radial flow, relative to the strength of the azimuthal flow. A limitation of our fluid model is that it is nondispersive.Comment: 30 pages, LaTeX, 4 ps figures. Expanded discussion especially in section 6; 5 new references. Version to appear in Phys. Rev.

    Gene expression profiling to study racial differences after heart transplantation.

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    BackgroundThe basis for increased mortality after heart transplantation in African Americans and other non-Caucasian racial groups is poorly defined. We hypothesized that increased risk of adverse events is driven by biologic factors. To test this hypothesis in the Invasive Monitoring Attenuation through Gene Expression (IMAGE) study, we determined whether the event rate of the primary outcome of acute rejection, graft dysfunction, death, or retransplantation varied by race as a function of calcineurin inhibitor (CNI) levels and gene expression profile (GEP) scores.MethodsWe determined the event rate of the primary outcome, comparing racial groups, stratified by time after transplant. Logistic regression was used to compute the relative risk across racial groups, and linear modeling was used to measure the dependence of CNI levels and GEP score on race.ResultsIn 580 patients monitored for a median of 19 months, the incidence of the primary end point was 18.3% in African Americans, 22.2% in other non-Caucasians, and 8.5% in Caucasians (p < 0.001). There were small but significant correlations of race and tacrolimus trough levels to the GEP score. Tacrolimus levels were similar among the races. Of patients receiving tacrolimus, other non-Caucasians had higher GEP scores than the other racial groups. African American recipients demonstrated a unique decrease in expression of the FLT3 gene in response to higher tacrolimus levels.ConclusionsAfrican Americans and other non-Caucasian heart transplant recipients were 2.5-times to 3-times more likely than Caucasians to experience outcome events in the Invasive Monitoring Attenuation through Gene Expression study. The increased risk of adverse outcomes may be partly due to the biology of the alloimmune response, which is less effectively inhibited at similar tacrolimus levels in minority racial groups
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