12,224 research outputs found

    Enhancing li→3ljl_i \to 3 l_j with the Z0Z^0-penguin

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    Lepton flavor violation (LFV) has been observed in neutrino oscillations. For charged lepton FV decays only upper limits are known, but sizable branching ratios are expected in many neutrino mass models. High scale models, such as the classical supersymmetric seesaw, usually predict that decays li→3ljl_i \to 3 l_j are roughly a factor α\alpha maller than the corresponding decays li→ljγl_i \to l_j \gamma. Here we demonstrate that the Z0Z^0-penguin diagram can give an enhancement for decays li→3ljl_i \to 3 l_j in many extensions of the MSSM. We first discuss why the Z0Z^0-penguin is not dominant in the MSSM with seesaw and show that much larger contributions from the Z0Z^0-penguin are expected in general. We then demonstrate the effect numerically in two example models, namely, the supersymmetric inverse seesaw and R-parity violating supersymmetry.Comment: 5 pages; v2: minor corrections, final version to appear in PR

    Curvature(s) of a light wavefront in a weak gravitational field

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    The geometry of a light wavefront evolving from a flat wavefront under the action of weak gravity field in the 3-space associated to a post-Newtonian relativistic spacetime, is studied numerically by means of the ray tracing method.Comment: 3 pages, 1 fig, Talk given by JFPS at the 12th Marcel Grossmann conference (Paris, July, 2009), submitted to the Proceeding

    Geometry of an accelerated rotating disk

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    We analyze the geometry of a rotating disk with a tangential acceleration in the framework of the Special Theory of Relativity, using the kinematic linear differential system that verifies the relative position vector of time-like curves in a Fermi reference. A numerical integration of these equations for a generic initial value problem is made up and the results are compared with those obtained in other works.Comment: 10 pages, LaTeX, 2 eps figs; typos corrected, added reference, minor changes; submitte

    Ar:N2_2 - a non-universal glass

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    The bias energies of various two-level systems (TLSs) and their strengths of interactions with the strain are calculated for Ar:N2_2 glass. Unlike the case in KBr:CN, a distinct class of TLSs having weak interaction with the strain and untypically small bias energies is not found. The addition of CO molecules introduces CO flips which form such a class of weakly interacting TLSs, albeit at much lower coupling than are typically observed in solids. We conclude that because of the absence of a distinct class of weakly interacting TLSs, Ar:N2_2 is a non-universal glass, the first such system in three dimensions and in ambient pressure. Our results further suggest that Ar:N2_2:CO may show universal properties, but at temperatures lower than ≈0.1\approx 0.1 K, much smaller than typical temperature ≈3\approx 3 K associated with universality, because of the untypical softness of this system. Our results thus shed light on two long standing questions regarding low temperature properties of glasses: the necessary and sufficient conditions for quantitative universality of phonon attenuation, and what dictates the energy scale of ≈3\approx 3 K below which universality it typically observed.Comment: 6 pages, 2 figures, results for excitations densities of states are added, presentation improve

    Predicting charged lepton flavor violation from 3-3-1 gauge symmetry

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    The simplest realization of the inverse seesaw mechanism in a SU(3)C⊗SU(3)L⊗U(1)XSU(3)_C \otimes SU(3)_L \otimes U(1)_X gauge theory offers striking flavor correlations between rare charged lepton flavor violating decays and the measured neutrino oscillations parameters. The predictions follow from the gauge structure itself without the need for any flavor symmetry. Such tight complementarity between charged lepton flavor violation and oscillations renders the scenario strictly testable.Comment: 7 pages, 2 figures; v2: discussion extended. Matches version published in PR
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