Neutrino masses, muon g−2, and lepton-flavour violation in the supersymmetric see-saw model

In the light of the recent muon (g_μ−2) result by the E821 experiment at the Brookhaven National Laboratory, we study the event rates of the charged lepton-flavour-violating (LFV) processes in the supersymmetric standard model (SUSY SM) with the heavy right-handed neutrinos (SUSY see-saw model). Since the left-handed sleptons get the LFV masses via the neutrino Yukawa interaction in this model, the event rate of μ→eγ and the SUSY-SM correction to (g_μ−2)/2 (δa_μ^SUSY) are strongly correlated. When the left-handed sleptons have a LFV mass between the first and second generations ( ) in the mass matrix, it should be suppressed by 10⁻³ (10⁻⁹/δa_μ^SUSY) compared with the diagonal components (m_SUSY²), from the current experimental bound on μ→eγ. The recent (g_μ−2) result indicates δa_μ^SUSY10⁻⁹. The future charged LFV experiments could cover . These experiments will give a significant impact on the flavour models and the SUSY-breaking models. In the SUSY see-saw model is proportional to square of the tau-neutrino Yukawa-coupling constant. In the typical models where the neutrino-oscillation results are explained and the top-quark and tau-neutrino Yukawa couplings are unified at the GUT scale, a large LFV mass of is generated, and the large LFV event rates are predicted. We impose a so-called no-scale condition for the SUSY-breaking parameters at the GUT scale, which suppresses the FCNC processes, and derive the conservative lower bound on μ→eγ. The predicted Br(μ→eγ) could be covered at the future LFV experiments.