Measurement of the ${\tau }^{-}\to K^{-}{\pi }^0{\nu }_{\tau }$ branching fraction

A measurement of the ${\tau }^{-}\to K^{-}{\pi }^0{\nu }_{\tau }$ branching fraction has been made using $230.2{\mathrm{fb}}^{-1}$ of data recorded by the BABAR detector at the PEP-II $e^{+}{e}^{-}$ collider, located at the Stanford Linear Accelerator Center (SLAC), at a center-of-mass energy $\sqrt{s}$ close to 10.58 GeV. We measure $\mathcal{B}({\tau }^{-}\to K^{-}{\pi }^0{\nu }_{\tau })=(0.416\pm 0.003(\mathrm{stat})\pm 0.018(\mathrm{syst}))\%$.

Figure 1

Distribution of the reconstructed $K^{-}{\pi }^0$ mass for the combined sample in linear (top) and logarithmic (bottom) scale. The dots are the data, while the histograms are background MC events with selection and efficiency corrections: $\tau$ background (dashed line), $q\overline{q}$ (dash-dotted line), ${\mu }^{+}{\mu }^{-}$ (dotted line).