Evidence for $B^{-}\to {\tau }^{-}{\overline{\nu }}_{\tau }$ with a Hadronic Tagging Method Using the Full Data Sample of Belle

In this work, we measure the branching fraction of $B^{-}\to {\tau }^{-}{\overline{\nu }}_{\tau }$ using the full ${\rm Y}\left(4S\right)$ data sample containing $772\times {10}^6$$B\overline{B}$ pairs collected with the Belle detector at the KEKB asymmetric-energy $e^{+}{e}^{-}$ collider. Events with $B\overline{B}$ pairs are tagged by reconstructing one of the $B$ mesons decaying into hadronic final states, and $B^{-}\to {\tau }^{-}{\overline{\nu }}_{\tau }$ candidates are detected in the recoil. We discover evidence for $B^{-}\to {\tau }^{-}{\overline{\nu }}_{\tau }$ with a significance of 3.0 standard deviations including systematic errors and measure a branching fraction $B(B^{-}\to {\tau }^{-}{\overline{\nu }}_{\tau })=\left[{0.72}_{-0.25}^{+0.27}\right(\mathrm{stat})\pm 0.11(\mathrm{syst}\left)\right]\times {10}^{-4}$.