Leading logarithmic QCD corrections to the Bs → γγ decay rate including long-distance effects through Bs → φγ → γγ

Abstract We present leading logarithmic QCD corrections to the decay B s → γγ in the Standard Model. Further, the form factor F 1 (0) of B s → φγ is calculated in the framework of QCD sum rules and found to be in agreement with the result existing in the literature. Using Vector Meson Dominance model, the amplitude for B s → φγ → γγ is calculated as an estimate of the O 7 -type contributions to the long-distance effects in the B s → γγ decay. The resulting branching ratio B (B s → γγ) SD+LD o 7 is analysed in view of its strong dependence on the non-perturbative parameter Λ s , describing bound state effects, and the renormalization scale μ.