Measurement of the B→Xsγ branching fraction and photon energy spectrum using the recoil method

We present a measurement of the branching fraction and photon-energy spectrum for the decay B→X_sγ using data from the BABAR experiment. The data sample corresponds to an integrated luminosity of 210fb^-1, from which approximately 680 000 B Bmacr 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 B(B→X_sγ)=(3.66±0.85_stat±0.60_syst)×10^-4 for photon energies E_γ 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 m_b and μ_π². In addition, measurements of the direct CP asymmetry and isospin asymmetry are presented.