Lepton-Flavor Violation via Right-Handed Neutrino Yukawa Couplings in Supersymmetric Standard Model

Abstract

Various lepton-flavor violating (LFV) processes in the supersymmetric standard model with right-handed neutrino supermultiplets are investigated in detail. It is shown that large LFV rates are obtained when $\tan {\hat{I}}^2$ is large. In the case where the mixing matrix in the lepton sector has a similar structure as the Kobayashi-Maskawa matrix and the third-generation Yukawa coupling is as large as that of the top quark, the branching ratios can be as large as $Br(\hat{I}¼\to e{\hat{I}}^3)\simeq 10^{-11}$ and $Br(\ddot{I}„\to \hat{I}¼{\hat{I}}^3)\simeq 10^{-7}$, which are within the reach of future experiments. If we assume a large mixing angle solution to the atmospheric neutrino problem, rate for the process $\ddot{I}„\to \hat{I}¼{\hat{I}}^3$ becomes larger. We also discuss the difference between our case and the case of the minimal $SU(5)$ grand unified theory.