Patterns of Lepton-Flavour Violation Motivated by Decoupling and Sneutrino Inflation

Abstract We present predictions for flavour-violating charged-lepton decays induced by the seesaw mechanism implemented within the constrained minimal supersymmetric standard model (CMSSM) with universal input soft supersymmetry breaking terms. We assume that one heavy singlet neutrino almost decouples from the seesaw mechanism, as suggested by the pattern of light neutrino masses and mixing angles. This is suggested independently by sneutrino inflation with a low reheating temperature, T RH ≲10 7 GeV , so as to avoid overproducing gravitinos. This requirement further fixes the mass of the weakly-coupled sneutrino, whose decays may lead to leptogenesis. We find that BR ( μ → eγ )≳10 −13 but BR ( τ → μγ )≲10 −9 in the bulk of the acceptable parameter space, apart from a few isolated points. The ratio BR ( μ → eγ )/ BR ( τ → eγ ) depends on only one complex parameter, and is particularly interesting to compare with experiment.