$\bar{B}\to D^{(\ast )}{\tau }^{-}{\bar{\nu }}_{\tau }$ and Related Tauonic Topics at Belle

Abstract

The decays $\bar{B}\to D^{(\ast )}{\tau }^{-}{\bar{\nu }}_{\tau }$ are good probes to new physics beyond the Standard Model. The ratios of branching fractions $R(D^{(\ast )})\equiv BF(\bar{B}\to D^{(\ast )}{\tau }^{-}{\bar{\nu }}_{\tau })/BF(\bar{B}\to D^{(\ast )}{\ell }^{-}{\bar{\nu }}_{\ell })$ (where ${\ell }^{-}=e^{-},{\mu }^{-}$) measured by Belle, BaBar and LHCb show 3.9$\sigma$ deviation from the SM expectations as of 2015. In 2016, the Belle collaboration has shown two new measurements for the $\bar{B}\to D^{(\ast )}{\tau }^{-}{\bar{\nu }}_{\tau }$ decay. These include the first application of the semileptonic tagging to the $R(D^{\ast })$ measurement and the first measurement of the $\tau$ polarization using the hadronic $\tau$ decays. We also review the two measurements for $B^{-}\to {\tau }^{-}{\bar{\nu }}_{\tau }$ at Belle. Along with these results, compatibility with the type-II Two-Higgs-Doublet Model is discussed.

8 pages, 7 figures, proceedings of 52nd Rencontres de Moriond EW, 18-25 March 2017

Cited by in corpus (2)

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