Measurement of the branching fraction ratios $R(D^{+})$ and $R(D^{*+})$ using muonic $τ$ decays (2406.03387v2)
Abstract: The branching fraction ratios of $\overline{B}0\to D+\tau-\overline{\nu}_{\tau}$ and $\overline{B}0\to D{*+}\tau-\overline{\nu}_{\tau}$ decays are measured with respect to their muonic counterparts, using a data sample corresponding to an integrated luminosity of 2.0 fb${-1}$ collected by the LHCb experiment in proton-proton collisions at $\sqrt{s} = 13$ TeV. The reconstructed final states are formed by combining $D+$ mesons with $\tau-\to\mu-\overline{\nu}{\mu}\nu{\tau}$ candidates, where the $D+$ is reconstructed via the $D+\to K-\pi+\pi+$ decay. The results are \begin{align*} R(D{+}) &= 0.249 \pm 0.043 \pm 0.047, R(D{*+}) &= 0.402 \pm 0.081\pm 0.085, \end{align*} where the first uncertainties are statistical and the second systematic. The two measurements have a correlation coefficient of $-0.39$ and are compatible with the Standard Model.