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

In the light of the recent muon (g(mu) - 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-handled sleptons get the LFV masses via the neutrino Yukawa interaction in this model, the event rate of mu --> e gamma and the SUSY-SM correction to (g(mu) - 2)/2 (deltaa(mu)(SUSY)) are strongly correlated. When the left-handed sleptons have a LFV mass between the first and second generations ((m((L) over tilde)(2))(12)) in the mass matrix, it should be suppressed by similar to 10(-3) (10(-9)/deltaa(mu)(SUSY)) compared with the diagonal components (m(SUSY)(2)), from the current experimental bound on mu --> e gamma. The recent (g(mu) - 2) result indicates deltaa(mu)(SUSY) similar to 10(-9). The future charged LFV experiments could cover (m((L) over tilde)(2))(12)/m(SUSY)(2) greater than or similar to 10(-(5-6)). These experiments will give a significant impact on the flavour models and the SUSY-breaking models. in the SUSY see-saw model (m((L) over tilde)(2))(12) 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 (m((L) over tilde)(2))(12)/m(SUSY)(2) greater than or similar to 10(-4) 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 mu --> e gamma. The predicted Br(mu --> e gamma) could be covered at the future LFV experiments. (C) 2001 Elsevier Science B.V. All rights reserved.