Weak Radiative B-Meson Decay Beyond Leading Logarithms

Abstract

We present our results for three-loop anomalous dimensions necessary in analyzing $B\to X_s\gamma$ decay at the next-to-leading order in QCD. We combine them with other recently calculated contributions, obtaining a practically complete next-to-leading order prediction for the branching ratio $\mathcal{B}(B\to X_s\gamma )=(3.28\pm 0.33)\times 10^{-4}$. The uncertainty is more than twice smaller than in the previously available leading order theoretical result. The Standard Model prediction remains in agreement with the CLEO measurement at the $2\sigma$ level.

Comments: Formulae for f_88(delta), f_78(delta), f_12(delta) and the first equation in Appendix B corrected