相关论文: Measuring B -> tau nu and B_c -> tau nu at the Z p…

The decays D(s)+- -> mu+- nu and D(s)+- -> tau+- nu have traditionally been used to measure the D(s)+- meson decay constant f_D(s). Recent measurements at CLEO-c and the B factories suggest a branching ratio for both decays somewhat higher…

We present a search for the decay B+ --> tau+ nu_tau using 467.8 x 10^6 B B-bar pairs collected at the Upsilon(4S) resonance with the BABAR detector at the SLAC PEP-II B-Factory. We select a sample of events with one completely…

We present a search for the decay B+ -->tau+ nu using 467.8 x 10^6 B B pairs collected at the Y(4S) resonance with the BaBar detector at the SLAC PEP-II B-Factory. We select a sample of events with one completely reconstructed B- in the…

We study the contribution of B_c mesons to the search for B->tau nu decays. We find that at LEP the contributions from B_u and B_c mesons can be comparable. This observation can have a relevant impact on the extraction of constraints on new…

We demonstrate that a measurement of the impact parameter in one-prong tau decay can be useful for the determination of the Higgs boson parity in the H/A --> tau tau; tau --> rho nu decay chain. We have estimated that for a detection set-up…

Based on the full BaBar data sample, we report improved measurements of the ratios R(D(*)) = B(B -> D(*) Tau Nu)/B(B -> D(*) l Nu), where l is either e or mu. These ratios are sensitive to new physics contributions in the form of a charged…

We present a search for the decay B^+ --> tau^+ nu using $383 \times 10^{6}}$ BBbar pairs collected at the Upsilon(4S) resonance with the BABAR detector at the SLAC PEP-II B Factory. We select a sample of events with one completely…

We present the recent BaBar searches for the leptonic decay B+ --> tau+ nu and for the rare decay B --> K(*) nu nubar, using a data sample of about 470 x 10^6 BB pairs. Both searches use a technique in which one B meson is hadronically…

B physics is sensitive to the effects of Higgs bosons in the Minimal Supersymmetric Standard Model, if the parameter tan beta is large. I briefly summarise the role of B -> mu+ mu- and B -> tau nu in the hunt for new Higgs effects and…

In the Standard Model, scalar contributions to leptonic and semileptonic decays are helicity suppressed. The hypothesis of additional physical neutral/charged Higgses can enhance such scalar contributions and give detectable effects…

A light non-standard Higgs boson decaying mainly into $\tau^+\tau^-$ has not been yet ruled out by LEP searches in several scenarios. We verify that, in the context of the Next-to-Minimal-Supersymmetric Standard Model, a low-mass CP-odd…

Spin correlations for tau lepton decays are included in the Pythia 8 event generation software and the spin correlations for the decays of tau leptons produced from electroweak and Higgs bosons are calculated. Decays of the tau lepton using…

Based on the full BaBar data sample, we report improved measurements of the ratios R(D(*)) = B(B -> D(*) Tau Nu)/B(B -> D(*) l Nu), where l is either e or mu. These ratios are sensitive to new physics contributions in the form of a charged…

The inclusive branching ratio for the process b -> tau nu X has been measured using hadronic Z decays collected by the OPAL experiment at LEP in the years 1992-2000. The result is: BR(b -> tau nu X) = (2.78 +/- 0.18 +/- 0.51)% This…

We present results on the determination of the observable ratio R=BR(H^+ -> \tau \nu)/BR(H^+ -> t b-bar) of charged Higgs boson decay rates as a discriminant quantity between Supersymmetric and non-Supersymmetric models. Simulation of…

The recent observations of the purely leptonic decay $\Ds \to \mu^+ \nu_{\mu}$ and $\tau^+\nu_{\tau}$ at CLEO-c and $B$ factory may allow a possible contribution from a charged Higgs boson. One such measurement of the decay constant…

We investigate the semileptonic and leptonic B decays, B to D^{(*)} tau nu and B to tau nu in our multi-Higgs-doublet models, while keeping in mind the enhancement of the top forward-backward (FB) asymmetry (A^t_{FB}) at the Tevatron. In…

Inclusive branching ratios involving b to tau transitions are measured in approximately four million hadronic Z decays collected by the ALEPH detector at LEP. The fully-inclusive branching ratio b -> tau nu X and the semi-inclusive…

We discuss semileptonic and leptonic B decays, B to D^{(*)} tau nu and B to tau nu, in the chiral U(1)' models which were proposed by the present authors in the context of the top forward-backward asymmetry (A^t_FB) observed at the…

A sizable excess with respect to the SM expectation has been reported recently by the BaBar collaboration in the decay rates B -> D(*) Tau Nu, normalized by the corresponding light lepton modes. A violation of lepton flavor universality as…