12,224 research outputs found
Enhancing with the -penguin
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 are roughly a factor maller than the corresponding decays . Here we demonstrate that the -penguin diagram can give an
enhancement for decays in many extensions of the MSSM. We first
discuss why the -penguin is not dominant in the MSSM with seesaw and show
that much larger contributions from the -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
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
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:N - a non-universal glass
The bias energies of various two-level systems (TLSs) and their strengths of
interactions with the strain are calculated for Ar:N 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:N
is a non-universal glass, the first such system in three dimensions and in
ambient pressure. Our results further suggest that Ar:N:CO may show
universal properties, but at temperatures lower than K, much
smaller than typical temperature 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 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
The simplest realization of the inverse seesaw mechanism in a 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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