Te. Browder et al., SEARCH FOR B-]MU(NU)OVER-BAR(MU)GAMMA AND B-]E(NU)OVER-BAR(E)GAMMA, Physical review. D. Particles and fields, 56(1), 1997, pp. 11-16
We have searched for the decays B-->mu (v) over bar(mu)gamma and B-->e
(v) over bar(e) gamma in a sample of 2.7 x 10(6) charged B decays col
lected with the CLEO II detector. In the muon channel, we observe no c
andidates in the signal region and set an upper limit on the branching
fraction of B(B-->mu (v) over bar(mu)gamma) < 5.2 x 10(-5) at the 90%
confidence level. In the electron channel. we observe five candidates
in the signal region and set an upper limit on the branching fraction
of B(B-->e (v) over bar(e) gamma) < 2.0 x 10(-4) at the 90% confidenc
e level.