Tauonic B Decays in the Minimal Supersymmetric Standard Model

We study new physics effects on B decay processes including a final τ particle, namely B → Dτν and B → τν. An important feature of these processes is that a charged Higgs boson can contribute to the decay amplitude at the tree level in models such as Two Higgs Doublet Model and the Minimal Supersymmetric Standard Model (MSSM). We derive a resummed effective Lagrangian for charged-Higgs mediated interactions in the MSSM with the Minimal Flavor Violation. Including supersymmetric (SUSY) loop corrections for down-type-quark and charged-lepton Yukawa couplings, we calculate the branching ratios of the B → Dτν and B → τν processes. We find that SUSY correction due to gluino-sbottom diagrams can change the Higgs exchange contribution by ±50%, whereas stau-neutralino diagrams can make corrections up to 20%. We also discuss relationship between SUSY corrections in the tauonic decays and flavor changing neutral current processes such as Bs → µ + µ − and b → sγ.