Lepton flavor violation in lopsided models and a neutrino mass model

A widely adopted theoretical scheme to account for the neutrino oscillation phenomena is the see-saw mechanism together with the ``lopsided'' mass matrices, which is generally realized in the framework of supersymmetric grand unification. We will show that this scheme leads to large lepton flavor violation at low energy if supersymmetry is broken at the GUT or Plank scale. Especially, the branching ratio of $\mu\to e\gamma$ already exceeds the present experimental limit. We then propose a phenomenological model, which can account for the LMA solution to the solar neutrino problem and at the same time predict branching ratio of $\mu\to e\gamma$ below the present limit.Comment: 15 pages, 4 figure

Diffuse γ\gamma-rays and pˉ\bar{p} flux from dark matter annihilation -- a model for consistent results with EGRET and cosmic ray data

In this work we develop a new propagation model for the Galactic cosmic rays based on the GALPROP code, including contributions from dark matter annihilation. The model predicts compatible Galactic diffuse $\gamma$ ray spectra with EGRET data in all sky regions. It also gives consistent results of the diffuse $\gamma$ ray longitude and latitude distributions. Further the results for B/C, $^{10}$Be/$^9$Be, proton, electron and antiproton spectra are also consistent with cosmic ray measurements. In the model we have taken a universal proton spectrum throughout the Galaxy without introducing large fluctuation for the proton energy loss is negligible. The dark matter annihilation signals are `boosted' after taking the contribution from subhalos into account. Another interesting feature of the model is that it gives better description of the diffuse $\gamma$ rays when taking the source distribution compatible with supernova remnants data, which is different from previous studies.Comment: 29 pages, 13 figures; the published versio