B to Tau Leptonic and Semileptonic Decays

Book excerpt: Decays of B mesons to states involving [tau] leptons can be used as a tool to search for the effects of new physics, such as those involving a charged Higgs boson. The experimental status of the decays B → [tau][nu] and B → D{sup (*)}[tau][nu] is discussed, together with limits on new physics effects from current results. Leptonic and semileptonic decays of B mesons into states involving [tau] leptons remain experimentally challenging, but can prove a useful tool for constraining Standard Model parameters, and also offer to constrain the effects of any new physics that may exist including the presence of a charged Higgs boson.