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

We perform a detailed analysis of several mu-tau lepton flavour violating (LFV) processes, namely tau - muX (X = gamma, e(+)e(-), mu(+)mu(-), rho, pi, eta, eta'), Z --> mutau and Higgs boson decays into mutau. First we present a model independent operator analysis relevant to such decays, then we explicitly compute the LFV operator coefficients [and (gmu - 2)] in a general unconstrained MSSM framework, allowing slepton mass matrices to have large mu-tau entries. We systematically study the role and the interplay of dipole and non-dipole operators, showing how the rates and the mutual correlations of those LFV decays change in different regions of the MSSM parameter space. Values of the LFV branching ratios Z in the experimentally interesting range 10(-9)-10(-7) can be achieved. For at least two MSSM Higgs bosons, the branching ratio of the LFV decay into mutau can reach values of order 10(-4). (C) 2004 Elsevier B.V. All rights reserved.