Solar and atmospheric neutrino oscillations and lepton flavor violation in supersymmetric models with right-handed neutrinos

Taking the solar and the atmospheric neutrino experiments into account we discuss the lepton flavor violating processes, such as tau-->mu gamma or mu-->e gamma, in the minimal supersymmetric standard model with right-handed neutrinos (MSSMRN) and the supersymmetric SU(5) grand unified theory with right-handed neutrinos [SU(5)RN]. The predicted branching ratio of mu-->e gamma in the MSSMRN with the Mikheyev-Smirnov-Wolfenstein (MSW) large angle solution is so large that it goes beyond the current experimental bound if the second-generation right-handed Majorana mass M-nu 2 is greater than similar to 10(13)(similar to 10(14)) GeV for tan beta=30(3). When we take the MSW small angle solution, the mu-->e gamma rate is at most about 1/100 of that of the MSW large angle solution. The "just so" solution implies 10(-5) of that of the MSW large angle solution. Also, in the SU(5)RN the large mu-->e gamma rate naturally follows from the MSW large angle solution, and the predicted rate is beyond the current experimental bound if the typical right-handed Majorana mass M-N is larger than similar to 10(13)(similar to 10(14)) GeV for tan beta=30(3), similarly to the MSSMRN. We show the multimass insertion formulas and their applications to tau-->mu gamma and mu-->e gamma. [S0556-2821(99)03909-0].