Evidence of the purely leptonic decay B-→τ-ν̄τ

We present the first evidence of the decay B-→τ-ν̄τ, using 414fb-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. We detect the signal with a significance of 3.5 standard deviations including systematics and measure the branching fraction to be B(B-→τ-ν̄τ)=(1.79-0.49+0.56(stat) -0.51+0.46(syst))×10-4. This implies that fB=0.229-0.031+0.036(stat)-0. 037+0.034(syst)GeV and is the first direct measurement of this quantity. © 2006 The American Physical Society.

Published in:
Physical Review Letters, 97, 25, 251802
Other identifiers:
Scopus: 2-s2.0-33845790610
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 Record created 2010-11-05, last modified 2018-05-17

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