Measurement of B+→τ+ντ at Belle

We present the first evidence of the decay B+→τ+ντ, using 414 fb−1 of data collected at the ϒ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. Events are tagged by fully reconstructing one of the B mesons in hadronic modes. The significance of the signal is 3.5 standard deviations including systematics, and the branching fraction is measured to be . This implies that ; this is the first direct measurement of this quantity.