785 research outputs found

    Towards the Theory of Non--Abelian Tensor Fields I

    Full text link
    We present a triangulation--independent area--ordering prescription which naturally generalizes the well known path ordering one. For such a prescription it is natural that the two--form ``connection'' should carry three ``color'' indices rather than two as it is in the case of the ordinary one--form gauge connection. To define the prescription in question we have to define how to {\it exponentiate} a matrix with three indices. The definition uses the fusion rule structure constants.Comment: 22 pages, 18 figure

    Superkamiokande and solar antineutrinos

    Get PDF
    We propose to exploit the angular distribution of the positrons emitted in the inverse beta decay to extract a possible antineutrino signal from the Superkamiokande background. From the statistics collected in just 101.9 days one obtains a model independent upper bound on the antineutrino flux (for energy greater than 8.3 MeV) Phi < 9*10^4 cm^-2 s^-1 at the 95% C.L. By assuming the same energy spectrum as for the 8B neutrinos, the 95% C.L. bound is Phi < 6*10^4 cm^-2 s^-1. Within three years of data taking, the sensitivity to neutrino-antineutrino transition probability will reach the 1% level, thus providing a stringent test of hybrid oscillation models.Comment: 7 pages, 1 figure, Late

    Quantum field theoretic approach to neutrino oscillations in matter

    Full text link
    We consider neutrino oscillations in non-uniform matter in a quantum field theoretic (QFT) approach, in which neutrino production, propagation and detection are considered as a single process. We find the conditions under which the oscillation probability can be sensibly defined and demonstrate how the properly normalized oscillation probability can be obtained in the QFT framework. We derive the evolution equation for the oscillation amplitude and discuss the conditions under which it reduces to the standard Schr\"odinger-like evolution equation. It is shown that, contrary to the common usage, the Schr\"odinger-like evolution equation is not applicable in certain cases, such as oscillations of neutrinos produced in decays of free pions provided that sterile neutrinos with Δm2≳1\Delta m^2\gtrsim 1 eV2^2 exist.Comment: LaTeX, 24 pages + 16 pages of appendices, 1 figure. V2: typos correcte

    Reheat temperature in supersymmetric hybrid inflation models

    Full text link
    The allowed range of parameters for supersymmetric hybrid inflation and its extensions are investigated. The lower bound on the reheat temperature T_r in these models with hierarchical right handed neutrinos is found to be 3*10^7 GeV. (T_r as low as 100 GeV is possible for quasi degenerate right handed neutrinos.) We also present revised estimates for the scalar spectral index and the symmetry breaking scale associated with inflation.Comment: 15 pages, 8 figures, revtex4. v2: minor changes, matches published versio

    Stimulated Neutrino Transformation with Sinusoidal Density Profiles

    Full text link
    Large amplitude oscillations between the states of a quantum system can be stimulated by sinusoidal external potentials with frequencies that are similar to the energy level splitting of the states or a fraction thereof. Situations when the applied frequency is equal to an integer fraction of the energy level splittings are known as parametric resonances. We investigate this effect for neutrinos both analytically and numerically for the case of arbitrary numbers of neutrino flavors. We look for environments where the effect may be observed and find that supernova are the one realistic possibility due to the necessity of both large densities and large amplitude fluctuations. The comparison of numerical and analytic results of neutrino propagation through a model supernova reveals it is possible to predict the locations and strengths of the stimulated transitions that occur.Comment: 14 pages, 6 figure

    De Sitter space and perpetuum mobile

    Full text link
    We give general arguments that any interacting non--conformal {\it classical} field theory in de Sitter space leads to the possibility of constructing a perpetuum mobile. The arguments are based on the observation that massive free falling particles can radiate other massive particles on the classical level as seen by the free falling observer. The intensity of the radiation process is non-zero even for particles with any finite mass, i.e. with a wavelength which is within the causal domain. Hence, we conclude that either de Sitter space can not exist eternally or that one can build a perpetuum mobile.Comment: 11 pages revtex, no figures. Added discussion to strengthen conclusio

    Neutrino Physics: Open Theoretical Questions

    Full text link
    We know that neutrino mass and mixing provide a window to physics beyond the Standard Model. Now this window is open, at least partly. And the questions are: what do we see, which kind of new physics, and how far "beyond"? I summarize the present knowledge of neutrino mass and mixing, and then formulate the main open questions. Following the bottom-up approach, properties of the neutrino mass matrix are considered. Then different possible ways to uncover the underlying physics are discussed. Some results along the line of: see-saw, GUT and SUSY GUT are reviewed.Comment: 17 pages, latex, 12 figures. Talk given at the XXI International Symposium on Lepton and Photon Interactions at High Energies, ``Lepton Photon 2003", August 11-16, 2003 - Fermilab, Batavia, IL US

    Supernova prompt neutronization neutrinos and neutrino magnetic moments

    Get PDF
    It is shown that the combined action of spin-flavor conversions of supernova neutrinos due to the interactions of their Majorana-type transition magnetic moments with the supernova magnetic fields and flavor conversions due to the mass mixing can lead to the transformation of \nu_e born in the neutronization process into their antiparticles \bar{\nu}_e. Such an effect would have a clear experimental signature and its observation would be a smoking gun evidence for the neutrino transition magnetic moments. It would also signify the leptonic mixing parameter |U_{e3}| in excess of 10^{-2}.Comment: LaTex, 25 pages, 3 figures. v4: Discussion section expanded, references added. Matches the published versio

    Resonant neutrino spin-flavor precession and supernova shock revival

    Get PDF
    A new mechanism of supernova shock revival is proposed, which involves resonant spin--flavor precession of neutrinos with a transition magnetic moment in the magnetic field of the supernova. The mechanism can be operative in supernovae for transition magnetic moments as small as 10−14ÎŒB10^{-14}\mu_B provided the neutrino mass squared difference is in the range Δm2∌(3  eV)2−(600  eV)2\Delta m^2 \sim (3 \;{\rm eV})^2-(600 \;{\rm eV})^2. It is shown that this mechanism can increase the neutrino--induced shock reheating energy by about 60\%.Comment: 16 pages, latex, 2 figures. added few reference
    • 

    corecore