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Recent experimental results on exclusive semi-tauonic B meson decays,B → D ( * ) τν, showing sizable deviations from the standard model prediction, suggest a new physics in which the structure of the relevant weak charged interaction may differ from that of the standard model. We study the exclusive semi-tauonic B decays in a model-independent manner using the most general set of four-Fermi interactions in order to clarify possible structures of the charged current in new physics. It turns out that correlations among observables including tau and D * polarizations and q 2 distributions are useful to distinguish possible new physics operators. Further, we investigate some interesting models to exhibit the advantage of our model-independent analysis. As a result, we find that two Higgs doublet models without tree-level flavor changing neutral currents (FCNC) and the minimal supersymmetric standard model with R-parity violation are unlikely to explain the present experimental data, while two Higgs doublet models with FCNC and a leptoquark model are consistent with the data.

A distinct peak is observed in the π ± ψ ′ invariant mass distribution near 4.43 GeV in B → Kπ ± ψ ′ decays. A fit using a Breit-Wigner resonance shape yields a peak mass and width of M = 4433 ± 4 (stat) ± 2 (syst) MeV and Γ = 45 +18 −13 (stat) +30 −13 (syst) MeV. The product branching fraction is determined to be B(B 0 → K ∓ Z ± (4430)) × B(Z ± (4430) → π ± ψ ′ ) = (4.1 ± 1.0(stat) ± 1.4(syst)) × 10 −5 , where Z ± (4430) is used to denote the observed structure. The statistical significance of the observed peak is 6.5σ. These results are obtained from a 605 fb −1 data sample that contains 657 million B B pairs collected near the Υ(4S) resonance with the Belle detector at the KEKB asymmetric energy e + e − collider.

We study effects of charged Higgs boson exchange in the B semileptonic decaysB → D ( * ) τν τ . Both branching ratio and τ polarization are examined. We use the recent experimental data on semileptonic B decays and the heavy quark effective theory in order to reduce theoretical uncertainty in the hadronic form factors. Theoretical uncertainty in the branching ratio is found to be rather small and that in the τ polarization is almost negligible. Their measurements will give nontrivial constraints on the charged Higgs sector.