Branching fraction and photon energy spectrum for b -> s gamma

Abstract

We have measured the branching fraction and photon energy spectrum for the radiative penguin process b --> s gamma. We find B(b --> s gamma) = (3.21 +/- 0.43 +/- 0.27(-0.10)(+0.18)) x 10(-4), where the errors are statistical, systematic, and from theory corrections. We obtain first and second moments of the photon energy spectrum above 2.0 GeV, (E gamma) = 2.346 +/- 0.032 +/- 0.011 GeV, and (E-gamma(2)) - (E-gamma)(2) = 0.0226 +/- 0.0066 +/- 0.0020 GeV2, where the errors are statistical and systematic. From the first moment, we obtain (in the modified minimal subtraction renormalization scheme, to order 1/M-B(3) and beta (o)alpha (2)(s)) the heavy quark effective theory parameter <(<Lambda>)over bar> = 0.35 +/- 0.08 +/- 0.10 GeV.