Evidence for B-→τ-ν¯τ with a Hadronic Tagging Method Using the Full Data Sample of Belle

We measure the branching fraction of B^-→τ^-ν¯_τ using the full Υ(4S) data sample containing 772×10⁶ BB¯ pairs collected with the Belle detector at the KEKB asymmetric-energy e⁺e^- collider. Events with BB¯ pairs are tagged by reconstructing one of the B mesons decaying into hadronic final states, and B^-→τ^-ν¯_τ candidates are detected in the recoil. We find evidence for B^-→τ^-ν¯_τ with a significance of 3.0 standard deviations including systematic errors and measure a branching fraction B(B^-→τ^-ν¯_τ)=[0.72_-0.25^+0.27(stat)±0.11(syst)]×10^-4.