10,697 research outputs found

    Super-Kamiokande data and atmospheric neutrino decay

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    Neutrino decay has been proposed as a possible solution to the atmospheric neutrino anomaly, in the light of the recent data from the Super-Kamiokande experiment. We investigate this hypothesis by means of a quantitative analysis of the zenith angle distributions of neutrino events in Super-Kamiokande, including the latest (45 kTy) data. We find that the neutrino decay hypothesis fails to reproduce the observed distributions of muons.Comment: 6 pages (RevTeX) + 2 figures (Postscript

    Probing finite size effects in (λΦ4)4(\lambda \Phi^4)_4 MonteCarlo calculations

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    The Constrained Effective Potential (CEP) is known to be equivalent to the usual Effective Potential (EP) in the infinite volume limit. We have carried out MonteCarlo calculations based on the two different definitions to get informations on finite size effects. We also compared these calculations with those based on an Improved CEP (ICEP) which takes into account the finite size of the lattice. It turns out that ICEP actually reduces the finite size effects which are more visible near the vanishing of the external source.Comment: LATTICE98(Gauge, Higgs and Yukawa Models

    Light Sterile Neutrinos from Large Extra Dimensions

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    An experimentally verifiable Higgs-triplet model of neutrino masses from large extra dimensions was recently proposed. We extend it to accomodate a light sterile neutrino which also mixes with the three active neutrinos. A previously proposed phenomenological model of four neutrinos (\underline {the only viable such model now left}, in view of the latest atmospheric and solar neutrino-oscillation data) is specifically realized.Comment: 10 pages, no figure, remarks and references adde

    Mass Determination from Constraint Effective Potential

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    The Constraint Effective Potential (CEP) allows a determination of the mass and other quantities directly, without relying upon asymptotic correlator decays. We report and discuss the results of some mass calculations in (λΦ4)4(\lambda \Phi^4)_4, obtained from CEP and our improved version of CEP (ICEP).Comment: LATTICE99(Higgs, Yukawa, SUSY

    Neutrino masses and mixing angles from leptoquark interactions

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    In this paper we show that the mixing between leptoquarks (LQ's) from different SU(2)lSU(2)_l multiplets can generate a non-trivial Majorana mass matrix for neutrinos through one loop self energy diagrams. Such mixing can arise from gauge invariant and renormalizable LQ-Higgs interaction terms after EW symmetry breaking. We use the experimental indication on neutrino oscillation to find constraints on specific combinations of LQ couplings to quark-lepton pairs and to the SM higgs boson. These constraints are compared with the ones from πeνˉe\pi\to e\bar {\nu}_e.Comment: The expressions for majorana mass matrix of neutrinos have been corrected so that they are symmetric. Final version to be published in Physical Review

    An application of decomposable maps in proving multiplicativity of low dimensional maps

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    In this paper we present a class of maps for which the multiplicativity of the maximal output p-norm holds when p is 2 and p is larger than or equal to 4. The class includes all positive trace-preserving maps from the matrix algebra on the three-dimensional space to that on the two-dimensional.Comment: 9 page

    The Dual Meissner Effect and Magnetic Displacement Currents

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    The dual Meissner effect is observed without monopoles in quenched SU(2)SU (2) QCD with Landau gauge-fixing. Magnetic displacement currents which are time-dependent Abelian magnetic fields play a role of solenoidal currents squeezing Abelian electric fields. Monopoles are not always necessary to the dual Meissner effect. The squeezing of the electric flux means the dual London equation and the massiveness of the Abelian electric fields as an asymptotic field. The mass generation of the Abelian electric fields is related to a gluon condensate 0\neq 0 of mass dimension 2.Comment: 4 pages, 5 Postscript figures, title modified, some references added, minor changes made ; Accepted for publication in Phys.Rev.Let

    Searching for νμντ\nu_\mu \to \nu_\tau Oscillations with Extragalactic Neutrinos

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    We propose a novel approach for studying νμντ\nu_\mu \to \nu_\tau oscillations with extragalactic neutrinos. Active Galactic Nuclei and Gamma Ray Bursts are believed to be sources of ultrahigh energy muon neutrinos. With distances of 100 Mpc or more, they provide an unusually long baseline for possible detection of νμντ\nu_\mu \to \nu_\tau with mixing parameters Δm2\Delta m^2 down to 101710^{-17}eV2^2, many orders of magnitude below the current accelerator experiments. By solving the coupled transport equations, we show that high-energy ντ\nu_\tau's, as they propagate through the earth, cascade down in energy, producing the enhancement of the incoming ντ\nu_\tau flux in the low energy region, in contrast to the high-energy νμ\nu_\mu's, which get absorbed. For an AGN quasar model we find the ντ\nu_\tau flux to be a factor of 2 to 2.5 larger than the incoming flux in the energy range between 10210^2 GeV and 10410^4 GeV, while for a GRB fireball model, the enhancement is 10%-27% in the same energy range and for zero nadir angle. This enhancement decreases with larger nadir angle, thus providing a novel way to search for ντ\nu_\tau appearance by measuring the angular dependence of the muons. To illustrate how the cascade effect and the ντ\nu_\tau final flux depend on the steepness of the incoming ντ\nu_\tau, we show the energy and angular distributions for several generic cases of the incoming tau neutrino flux, Fν0EnF_\nu^0 \sim E^{-n} for n=1,2 and 3.6. We show that for the incoming flux that is not too steep, the signal for the appearance of high-energy ντ\nu_\tau is the enhanced production of lower energy μ\mu and their distinctive angular dependence, due to the contribution from the τ\tau decay into μ\mu just below the detector.Comment: 11 pages, including 4 color figure

    Control of shock wave-boundary layer interactions by bleed in supersonic mixed compression inlets

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    An experimental investigation was conducted to determine the effect of bleed on a shock wave-boundary layer interaction in an axisymmetric mixed-compression supersonic inlet. The inlet was designed for a free-stream Mach number of 2.50 with 60-percent supersonic internal area contraction. The experiment was conducted in the NASA Lewis Research Center 10-Foot Supersonic Wind Tunnel. The effects of bleed amount and bleed geometry on the boundary layer after a shock wave-boundary layer interaction were studied. The effect of bleed on the transformed form factor is such that the full realizable reduction is obtained by bleeding of a mass flow equal to about one-half of the incident boundary layer mass flow. More bleeding does not yield further reduction. Bleeding upstream or downstream of the shock-induced pressure rise is preferable to bleeding across the shock-induced pressure rise

    Development of a Gd Loaded Liquid Scintillator for Electron Anti-Neutrino Spectroscopy

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    We report on the development and deployment of 11.3 tons of 0.1% Gd loaded liquid scintillator used in the Palo Verde reactor neutrino oscillation experiment. We discuss the chemical composition, properties, and stability of the scintillator elaborating on the details of the scintillator preparation crucial for obtaining a good scintillator quality and stability.Comment: 9 pages, 4 figures, submitted to NIM
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