On the double radiative decays of the BS-meson and μ-atom: BS → γγ, μ+e− → yy☆

Abstract B s -meson and μ + e − bound states' double radiative decays B S → γγ and μ + e − → yy are investigated in frames of standard description. Explicit and most general expressions for the relevant amplitudes are obtained. The GIM mechanism operation in both decays are shown in detail. The branching ratio of ∼ 10 −7 and relative share of the CP-odd state of final photons δ ≈ 0.4 are calculated for B S → yy . It is shown that the SM prediction for Br( μ + e − → γγ in case of the three known lepton generations is hopelessly small to be ever observed in a foreseen future. Nevertheless, it could be interesting to recalculate this decay, assuming presence of the fourth (heavy) generation, in the framework of both extensions of SM and beyond SM approaches.