796 research outputs found

    Impact of CP phases on SUSY particle production and decays

    Full text link
    We report on the results of a phenomenological study of top squarks (stop_{1,2}) and bottom squarks (sbottom_{1,2}) in the Minimal Supersymmetric Standard Model (MSSM) with complex parameters A_t, A_b, mu and M_1. In particular we focus on the CP phase dependence of the branching ratios of stop_{1,2} and sbottom_{1,2} decays. We find that the effect of the phases on the stop_{1,2} and sbottom_{1,2} decays can be quite significant in a large region of the MSSM parameter space. We also study a CP asymmetry in sfermion decays.Comment: 10 pages, 8 eps figures, LaTeX, uses JHEP3.cls; talk given at the International Workshop on Astroparticle and High Energy Physics (AHEP), Valencia, Spain, 14-18 Oct. 200

    Suppression of the Shear Viscosity in a "semi" Quark Gluon Plasma

    Full text link
    We consider QCD at temperatures T near Tc, where the theory deconfines. We distinguish between a "complete" Quark Gluon Plasma (QGP), where the vacuum expectation value of the renormalized Polyakov loop is near unity, essentially constant with T, and the "semi"-QGP, where the loop changes strongly with T. Lattice simulations indicate that in QCD, there is a semi-QGP from below Tc to a few times that. Using a semi-classical model, we compute the shear viscosity, eta, to leading order in perturbation theory. We find that near Tc, where the expectation value of the Polyakov loop is small, that eta/T^3 is suppressed by two powers of the loop. For heavy ions, this suggests that during the initial stages of the collision, hydrodynamic behavior at the LHC will be characterized by a shear viscosity which is significantly larger than that at RHIC.Comment: ReVTeX, 6 pages, 1 figure. The paper, including title and abstract, was extensively rewritten. The results are unchange

    The Evolution of the ISM in the Mildly Disturbed Spiral Galaxy NGC 4647

    Get PDF
    We present matched-resolution maps of HI and CO emission in the Virgo Cluster spiral NGC 4647. The galaxy shows a mild kinematic disturbance in which one side of the rotation curve flattens but the other side continues to rise. This kinematic asymmetry is coupled with a dramatic asymmetry in the molecular gas distribution but not in the atomic gas. An analysis of the gas column densities and the interstellar pressure suggests that the H2/HI surface density ratio on the east side of the galaxy is three times higher than expected from the hydrostatic pressure contributed by the mass of the stellar disk. We discuss the probable effects of ram pressure, gravitational interactions, and asymmetric potentials on the interstellar medium and suggest it is likely that a m=1 perturbation in the gravitational potential could be responsible for all of the galaxy's features. Kinematic disturbances of the type seen here are common, but the curious thing about NGC 4647 is that the molecular distribution appears more disturbed than the HI distribution. Thus it is the combination of the two gas phases that provides such interesting insight into the galaxy's history and into models of the interstellar medium.Comment: ApJ, accepte

    Neutrino Emission from Magnetized Proto-Neutron Stars in Relativistic Mean Field Theory

    Full text link
    We make a perturbative calculation of neutrino scattering and absorption in hot and dense hyperonic neutron-star matter in the presence of a strong magnetic field. We find that the absorption cross-sections show a remarkable angular dependence in that the neutrino absorption strength is reduced in a direction parallel to the magnetic field and enhanced in the opposite direction. This asymmetry in the neutrino absorbtion can be as much as 2.2 % of the entire neutrino momentum for an interior magnetic field of \sim 2 x 10^{17} G. We estimate the pulsar kick velocities associated with this asymmetry in a fully relativistic mean-field theory formulation. We show that the kick velocities calculated here are comparable to observed pulsar velocities.Comment: arXiv admin note: substantial text overlap with arXiv:1009.097

    Phenomenological theory of a scalar electronic order: application to skutterudite PrFe4P12

    Full text link
    By phenomenological Landau analysis, it is shown that a scalar order parameter with the point-group symmetry Γ1g\Gamma_{1g} explains most properties associated with the phase transition in PrFe4_4P12_{12} at 6.5 K. The scalar-order model reproduces magnetic and elastic properties in PrFe4_4P12_{12} consistently such as (i) the anomaly of the magnetic susceptibility and elastic constant at the transition temperature, (ii) anisotropy of the magnetic susceptibility in the presence of uniaxial pressure, and (iii) the anomaly in the elastic constant in magnetic field. An Ehrenfest relation is derived which relates the anomaly of the magnetic susceptibility to that of the elastic constant at the transition.Comment: 16 pages, 9 figure

    Alternation of Sound Location Induces Visual Motion Perception of a Static Object

    Get PDF
    Background: Audition provides important cues with regard to stimulus motion although vision may provide the most salient information. It has been reported that a sound of fixed intensity tends to be judged as decreasing in intensity after adaptation to looming visual stimuli or as increasing in intensity after adaptation to receding visual stimuli. This audiovisual interaction in motion aftereffects indicates that there are multimodal contributions to motion perception at early levels of sensory processing. However, there has been no report that sounds can induce the perception of visual motion. Methodology/Principal Findings: A visual stimulus blinking at a fixed location was perceived to be moving laterally when the flash onset was synchronized to an alternating left-right sound source. This illusory visual motion was strengthened with an increasing retinal eccentricity (2.5 deg to 20 deg) and occurred more frequently when the onsets of the audio and visual stimuli were synchronized. Conclusions/Significance: We clearly demonstrated that the alternation of sound location induces illusory visual motion when vision cannot provide accurate spatial information. The present findings strongly suggest that the neural representations of auditory and visual motion processing can bias each other, which yields the best estimates of externa

    Hard thermal loops, to quadratic order, in the background of a spatial 't Hooft loop

    Full text link
    We compute the simplest hard thermal loops for a spatial 't Hooft loop in the deconfined phase of a SU(N) gauge theory. We expand to quadratic order about a constant background field A_0 = Q/g, where Q is a diagonal, color matrix and g is the gauge coupling constant. We analyze the problem in sufficient generality that the techniques developed can be applied to compute transport properties in a "semi"-Quark Gluon Plasma. Notably, computations are done using the double line notation at finite N. The quark self-energy is a Q-dependent thermal mass squared, of order g^2T^2, where T is the temperature, times the same hard thermal loop as at Q=0. The gluon self-energy involves two pieces: a Q-dependent Debye mass squared, of order g^2T^2, times the same hard thermal loop as for Q=0, plus a new hard thermal loop, of order g^2T^3, due to the color electric field generated by a spatial 't Hooft loop.Comment: 52 pages, 10 figures; Eqs. (118), (137), and (158) have been corrected. We thank H. Nishimura and V. V. Skokov for pointing this ou

    γδ T cells affect IL-4 production and B-cell tolerance

    Get PDF
    γδ T cells can influence specific antibody responses. Here, we report that mice deficient in individual γδ T-cell subsets have altered levels of serum antibodies, including all major subclasses, sometimes regardless of the presence of αβ T cells. One strain with a partial γδ deficiency that increases IgE antibodies also displayed increases in IL-4–producing T cells (both residual γδ T cells and αβ T cells) and in systemic IL-4 levels. Its B cells expressed IL-4–regulated inhibitory receptors (CD5, CD22, and CD32) at diminished levels, whereas IL-4–inducible IL-4 receptor α and MHCII were increased. They also showed signs of activation and spontaneously formed germinal centers. These mice displayed IgE-dependent features found in hyper-IgE syndrome and developed antichromatin, antinuclear, and anticytoplasmic autoantibodies. In contrast, mice deficient in all γδ T cells had nearly unchanged Ig levels and did not develop autoantibodies. Removing IL-4 abrogated the increases in IgE, antichromatin antibodies, and autoantibodies in the partially γδ-deficient mice. Our data suggest that γδ T cells, controlled by their own cross-talk, affect IL-4 production, B-cell activation, and B-cell tolerance

    Development of a 66 kV-5 kA Class HTS Power Cable with IBAD/PLD REBCO Tapes

    Get PDF
    AbstractHigh temperature superconducting (HTS) cables are able to achieve large power capacity and low-loss power transmission. In the Japanese national project, Fujikura Ltd. worked on developing a 66 kV-5 kArms HTS power cable using high critical current (Ic) REBa2Cu3Ox (REBCO, RE = rare earth) tapes. One of the technical targets in this project is to reduce AC loss to less than 2W/m at 5 kArms. The REBCO tapes with 240 A/4mm-width of Ic at 77K, self field, which were fabricated by Ion-beam-assisted-deposition (IBAD) and Pulsed Laser Deposition (PLD) method, were applied to a HTS power cable in order to achieve extremely low AC loss. As a result, we have succeeded in developing a 20 m-long 66 kV-5 kArms HTS power cable. The measured AC loss was achieved 1.4W/m at 77K and 1.0W/m at 67K at 5 kArms
    • …
    corecore