Precision Measurement of the B→X[subscript s]γ Photon Energy Spectrum, Branching Fraction, and Direct CP Asymmetry A[subscript CP](B→X[subscript s+d]γ)

Abstract

The photon spectrum in the inclusive electromagnetic radiative decays of the B meson, B→X[subscript s]γ plus B→X[subscript d]γ, is studied using a data sample of (382.8±4.2)×10[superscript 6]Υ(4S)→BB̅ decays collected by the BABAR experiment at SLAC. The spectrum is used to extract the branching fraction B(B→X[subscript s]γ)=(3.21±0.33)×10[superscript -4] for E[subscript γ]>1.8  GeV and the direct CP asymmetry A[subscript CP](B→X[subscript s+d]γ)=0.057±0.063. The effects of detector resolution and Doppler smearing are unfolded to measure the photon energy spectrum in the B meson rest frame.United States. Dept. of Energy.National Science Foundation (U.S.

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