We report the measurement of the direct CP asymmetry in the radiative ¯B→Xs+dγ decay using a data sample of (772±11)×106 B¯B pairs collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. The CP asymmetry is measured as a function of the photon energy threshold. For E∗γ≥2.1 GeV, where E∗γ is the photon energy in the center-of-mass frame, we obtain ACP(¯B→Xs+dγ)=(2.2±3.9±0.9)%, consistent with the standard model prediction.
Physical Review Letters
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