Measurement of the Branching Fraction and Photon Energy Moments of B→Xsγ and ACP(B→Xs+dγ)

The photon spectrum in B→X_sγ decay, where X_s is any strange hadronic state, is studied using a data sample of 88.5×10⁶ e⁺e^-→Υ(4S)→BB¯ decays collected by the BABAR experiment at the Stanford Linear Accelerator Center. The partial branching fraction, ΔB(B→X_sγ)=(3.67±0.29(stat)±0.34(syst)±0.29(model))×10^-4, the first moment ⟨E_γ⟩=2.288±0.025±0.017±0.015GeV, and the second moment ⟨E_γ²⟩=0.0328±0.0040±0.0023±0.0036GeV² are measured for the photon energy range 1.9GeV<E_γ<2.7GeV. They are also measured for narrower E_γ ranges. The moments are then fit to recent theoretical calculations to extract the heavy quark expansion parameters m_b and μ_π² and to extrapolate the partial branching fraction to E_γ>1.6GeV. In addition, the direct CP asymmetry A_CP(B→X_s+dγ) is measured to be -0.110±0.115(stat)±0.017(syst).