Measurements of Isospin Asymmetry and Difference of Direct CP Asymmetries in Inclusive B→Xsγ Decays
Van Hulse, Charlotte Barbara
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Physical Review D 99(3) : (2019) // Article ID 032012
We report measurements of isospin asymmetry Delta(0-) and difference of direct CP asymmetries Delta A(CP) between charged and neutral B -> X-s gamma decays. This analysis is based on the data sample containing 772 x 10(6)B (B) over bar pairs that was collected with the Belle detector at the KEKB energy-asymmetric ethornecollider. Using a sum-of-exclusive technique with invariant X-s mass up to 2.8 GeV= c2, we obtain Delta(0-) = [0.48 +/- 1.49(stat) +/- 0.97(syst) +/- 1.15(f(+-)/f(00))]% and Delta A(CP) = [+3.69 +/- 2.65(stat) +/- 0.76(syst)]%, where the last uncertainty for.0-is due to the uncertainty on the production ratio of B+B- to B-0(B) over bar (0) in.o4Sthorn decays. The measured value of Delta(0-) is consistent with zero, allowing us to constrain the resolved photon contribution in the B -> X-s gamma, and improve the branching fraction prediction. The result for Delta A(CP) is consistent with the prediction of the SM. We also measure the direct CP asymmetries for charged and neutral B -> X-s gamma decays. All the measurements are the most precise to date.