ISSN - 00319007, EISSN - 10797114, Physical Review Letters, 2004, vol. 93, p. 131803-1
Evidence for B+ → ωl+v
The decay of B+ → ωl+ν (l = e or μ) in 78 fb-1 of υ(4S) data accumulated with the Belle detector is discussed. To estimate the neutrino momentum, the final state is fully reconstructed using the ω decay into π+π -π0, combined with detector hermeticity. It is found that corresponding to a branching fraction of (1.3±0.4±0.2±0.3) × 10-4, a signal of 414±125 events is found in the data, where the first two errors are systematic and statistical, respectively. The estimated form-factor uncertainty is reflected from the third error.