Measurement of the B --> Xs gamma Branching Fraction and Photon Energy Spectrum using the Recoil Method
Abstract
We present a measurement of the branching fraction and photon energy spectrum for the decay B --> Xs gamma using data from the BaBar experiment. The data sample corresponds to an integrated luminosity of 210 fb-1, from which approximately 680 000 BB events are tagged by a fully reconstructed hadronic decay of one of the B mesons. In the decay of the second B meson, an isolated high--energy photon is identified. We measure BR(B --> Xs gamma) = (3.66 +- 0.85stat +- 0.60syst) x 10-4 for photon energies Egamma above 1.9 GeV in the B rest frame. From the measured spectrum we calculate the first and second moments for different minimum photon energies, which are used to extract the heavy-quark parameters mb and mupi2. In addition, measurements of the direct CP asymmetry and isospin asymmetry are presented.
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