Measurement of Branching Fractions in Radiative B Decays to eta K gamma and Search for B Decays to eta' K gamma

The authors present measurements of the B → ηKγ branching fractions and upper limits for the B → η'Kγ branching fractions. For B+ → ηK+γ they also measure the time-integrated charge asymmetry. The data sample, collected with the BABAR detector at the Stanford Linear Accelerator Center, represents 232 x 106 produced B(bar B) pairs. The results for branching fractions and upper limits at 90% C.L. in units of 10-6 are: Β(B0 → ηK0γ) = 11.3-2.6+2.8 ± 0.6, Β(B+ → ηK+γ) = 10.0 ± 1.3 ± 0.5, Β(B0 → η'K0γ) < 6.6, Β(B+ → η'K+γ) < 4.2. The charge asymmetry in the decay B+ → ηK+γ is Αch = -0.09 ± 0.12 ± 0.01. The first errors are statistical and the second systematic