Evidence for Isospin Violation and Measurement of CP Asymmetries in B -˃ K*(892)gamma

Abstract

We report the first evidence for isospin violation in B -> K*gamma and the first measurement of the difference of CP asymmetries between B+->.K*(+)gamma and B-0 -> K-*0 gamma. This analysis is based on the data sample containing 772 x 10(6)BB pairs that was collected with the Belle detector at the KEKB energy-asymmetric e(+)e(-) collider. We find evidence for the isospin violation with a significance of 3.1 sigma, Delta(0+) = [+6.2 +/- 1.5(stat) +/- 0.6(syst) +/- 1.2(f (+-)/f(00))] %, where the third uncertainty is due to the uncertainty on the fraction of B+B- to (BB0)-B-0 production in gamma(4S) decays. The measured value is consistent with predictions of the standard model. The result for the difference of CP asymmetries is Delta A(CP) = [+2.4 +/- 2.8(stat) +/- 0.5(syst)] %, consistent with zero. The measured branching fractions and CP asymmetries for charged and neutral B meson decays are the most precise to date. We also calculate the ratio of branching fractions of B-0 -> K-*0 gamma to B-s(0) -> phi gamma.