Higgs-Mediatedτ→3μin the Supersymmetric Seesaw Model

Recent observations of neutrino oscillations imply nonzero neutrino masses and lepton flavor violation (LFV), most economically explained by the seesaw mechanism. Within the context of supersymmetry, LFV among the neutrinos can be communicated to the sleptons and from there to the charged leptons. We show that LFV can appear in the couplings of the neutral Higgs bosons, an effect that is strongly enhanced at large $\tan \beta$. We calculate the branching fraction for $\tau \to 3\mu$ and $\mu \to 3e$ mediated by Higgs and find they can be as large as ${10}^{-7}$ and $5\times {10}^{-14}$, respectively. These modes, along with $\tau \to \mu \gamma$ and $\mu \to e\gamma$, can provide key insights into the neutrino mass matrix.