Measurements of Direct CP Asymmetries in B→X_sγ Decays using Sum of Exclusive Decays


We measure the direct CP violation asymmetry, A_{CP}, in B→X_s and the isospin difference of the asymmetry, ΔA_{CP}, using 429 fb⁻¹ of data collected at ϒ(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 ten charged B final states and six neutral B final states. We find A_{CP} = +(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 A_{CP} for charged and neutral decay modes, ΔA_{CP} = +(5.0 ± 3.9 ± 1.5)%. Using the value of ΔA(CP), we also provide 68% and 90% confidence intervals on the imaginary part of the ratio of the Wilson coefficients corresponding to the chromomagnetic dipole and the electromagnetic dipole transitions.



B mesons, CP violation (Nuclear physics), Asymmetry, Isospin


©2014 American Physical Society