We report the measurement of the direct CP asymmetry in the radiative (B) over bar -> Xs+d gamma decay using a data sample of (772 +/- 11) x 10(6) B (B) over bar pairs collected at the Upsilon(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-gamma* >= 2.1 GeV, where E-gamma* is the photon energy in the center-of-mass frame, we obtain A(CP) ((B) over bar -> Xs+d gamma) = (2.2 +/- 3.9 +/- 0.9)%, consistent with the standard model prediction.
Matthias Finger, Konstantin Androsov, Jan Steggemann, Qian Wang, Anna Mascellani, Yiming Li, Varun Sharma, Xin Chen, Rakesh Chawla, Matteo Galli
Matthias Finger, Konstantin Androsov, Qian Wang, Jan Steggemann, Yiming Li, Anna Mascellani, Varun Sharma, Xin Chen, Rakesh Chawla, Matteo Galli