Higgs-mediated leptonic decays ofBsandBdmesons as probes of supersymmetry

Abstract

If $\mathrm{tan}\ensuremath{\beta}$ is large, down-type quark mass matrices and Yukawa couplings cannot be simultaneously diagonalized, and flavor violating couplings of the neutral Higgs bosons are induced at the one-loop level. These couplings lead to Higgs-mediated contributions to the decays ${B}_{s}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ and ${B}_{d}\ensuremath{\rightarrow}{\ensuremath{\tau}}^{+}{\ensuremath{\tau}}^{\ensuremath{-}},$ at a level that might be of interest for the current Fermilab Tevatron run, or possibly, at B factories. We evaluate the branching ratios for these decays within the framework of minimal gravity-, gauge- and anomaly-mediated supersymmetry breaking models, and also in $\mathrm{SU}(5)$ supergravity models with nonuniversal gaugino mass parameters at the grand unified theory scale. We find that the contribution from gluino loops, which seems to have been left out in recent phenomenological analyses, is significant. We explore how the branching fraction varies in these models, emphasizing parameter regions consistent with other observations.