Measurement of B decays to ϕKγ

Abstract

We search for the decays B − → ϕ K − γ and ¯¯¯ B 0 → ϕ ¯¯¯¯ K 0 γ in a data sample of 228 × 10 6 B ¯¯¯ B pairs collected at the Υ ( 4 S ) resonance with the BABAR detector. We measure the branching fraction B ( B − → ϕ K − γ ) = ( 3.5 ± 0.6 ± 0.4 ) × 10 − 6 and set an upper limit B ( ¯¯¯ B 0 → ϕ ¯¯¯¯ K 0 γ ) < 2.7 × 10 − 6 at the 90% confidence level. We also measure the direct C P asymmetry in B − → ϕ K − γ , A C P = ( − 26 ± 14 ± 5 ) % . The uncertainties are statistical and systematic, respectively.