Measurement of branching fractions in radiative B decays to ηKγ and search for B decays to η′Kγ

Abstract

We present measurements of the B → η K γ branching fractions and upper limits for the B → η ′ K γ branching fractions. For B + → η K + γ we also measure the time-integrated charge asymmetry. The data sample, collected with the BABAR detector at the Stanford Linear Accelerator Center, represents 232 × 10 6 produced B ¯¯¯ B pairs. The results for branching fractions and upper limits at 90% confidence level in units of 10 − 6 are: B ( B 0 → η K 0 γ ) = 11.3 + 2.8 − 2.6 ± 0.6 , B ( B + → η K + γ ) = 10.0 ± 1.3 ± 0.5 , B ( B 0 → η ′ K 0 γ ) < 6.6 , B ( B + → η ′ K + γ ) < 4.2 . The charge asymmetry in the decay B + → η K + γ is A ch = − 0.09 ± 0.12 ± 0.01 . The first errors are statistical and the second systematic.