The ( Q 7 , Q 1 , 2 ) contribution to B ¯ → X s γ B¯¯¯→Xsγ at O α s 2 O(α2s)

Interference between the photonic dipole operator Q 7 and the current-current operators Q 1,2 gives one of the most important QCD corrections to the ( B ¯ → X s γ B¯¯¯→Xsγ decay rate. So far, the O α s 2 O(α2s) ) part of this correction has been known in the heavy charm quark limit only ( m c ≫ m b / 2). Here, we evaluate this part at m c = 0, and use both limits in an updated phenomenological study. Our prediction for the CP- and isospin-averaged branching ratio in the Standard Model reads ℬ s γ S M = 3.36 ± 0.23 × 1 0 − 4 BSMsγ=(3.36±0.23)×10−4 for E γ > 1 . 6 GeV.