Tauonic B decays in the Minimal Supersymmetric Standard Model
We study new physics effects on B decay processes including a final $τ$ particle, namely $B \to D τν$ and $B \to τν$. 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 $B \to D τν$ and $B \to τν$ processes. We find that SUSY correction due to gluino-sbottom diagrams can change the Higgs exchange contribution by $\pm50$%, 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 $B_s \to μ^+μ^-$ and $b \to s γ$.