Anatomy and phenomenology of μ–τ lepton flavour violation in the MSSM

Abstract

We perform a detailed analysis of several mu-tau lepton flavour violating\n(LFV) processes, namely tau --> mu X (X = gamma, e+ e-, mu+ mu-, rho, pi, eta,\neta'), Z --> mu tau and Higgs boson decays into mu tau. First we present a\nmodel independent operator analysis relevant to such decays, then we explicitly\ncompute the LFV operator coefficients [and (g_\\mu -2)] in a general\nunconstrained MSSM framework, allowing slepton mass matrices to have large\nmu-tau entries. We systematically study the role and the interplay of dipole\nand non-dipole operators, showing how the rates and the mutual correlations of\nthose LFV decays change in different regions of the MSSM parameter space.Values\nof the LFV branching ratios in the experimentally interesting range\n10^{-9}-10^{-7} can be achieved. For at least two MSSM Higgs bosons, the\nbranching ratio of the LFV decay into mu tau can reach values of order 10^{-4}.\n