Measurements of Direct CP Asymmetries in B to Xs gamma decays using Sum of Exclusive Decays
Abstract
We measure the direct CP violation asymmetry, ACP, in B to Xs gamma and the isospin difference of the asymmetry, Delta ACP, using 429 fb-1 of data collected at Upsilon(4S) resonance with the BaBar detector at the PEP-II asymmetric-energy e+e- storage rings operating at the SLAC National Accelerator Laboratory. B mesons are reconstructed from 10 charged B final states and 6 neutral B final states. We find ACP = +(1.7 +- 1.9 +- 1.0)%, which is in agreement with the Standard Model prediction and provides an improvement on the world average. Moreover, we report the first measurement of the difference between ACP for charged and neutral decay modes, Delta ACP = +(5.0 +- 3.9 +- 1.5)%. Using the value of Delta ACP, we also provide 68% and 90% confidence intervals on the imaginary part of the ratio of the Wilson coefficients corresponding to the chromo-magnetic dipole and the electromagnetic dipole transitions.
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