Measurement of $\mathcal{R}(D)$ and $\mathcal{R}(D^{\ast })$ with a semileptonic tagging method

The Belle Collaboration, A. Abdesselam, I. Adachi +461

We report a measurement of the ratios of branching fractions $\mathcal{R}(D)=\mathcal{B}(\bar{B}\to D{\tau }^{-}{\bar{\nu }}_{\tau })/\mathcal{B}(\bar{B}\to D{\ell }^{-}{\bar{\nu }}_{\ell })$ and $\mathcal{R}(D^{…