Lepton flavor violation in the supersymmetric grand unified models with a lopsided mass matrix

The tiny neutrino masses measured in neutrino oscillation experiments can be naturally explained via a supersymmetric seesaw mechanism. If supersymmetry breaking is mediated by gravity, such seesaw models may predict observable lepton flavor violating effects. In this work, we investigate the lepton flavor violating process μ→eγ in supersymmetric seesaw models with a 'lopsided' charged lepton mass matrix. Constraints set by the muon anomalous magnetic moment are taken into account. We find that such models generally predict a branching ratio for μ→eγ far above the current experimental limit. Thus this process strongly constrains models of this type. Such restrictions suggest a novel form for the charged lepton mass matrix, featuring a 'lopsided' structure for elements between both the 2-3 and the 1-3 generations. This structure produces a very small 1-3 mixing and a large 1-2 mixing in the charged lepton sector, leading naturally to a small Br(μ→eγ) and to the large mixing angle solution for the solar neutrino problem