Complete Analyses on the Short-Distance Contribution of B s → l + l - γ in the Standard Model

Using the Bs meson wave function extracted from non-leptonic Bs decays, we evaluate the rare decays Bs → l+l− γ (l = e, μ) in the standard model, including contributions from all four kinds of diagrams. We focus on the contribution from the four-quark operators, which were not taken into account properly in previous studies. We find that the contribution is large, leading to the branching of Bs → l+l− γ being nearly enhanced by a factor 3 and up to 1.6 × 10−8. The predictions for such processes can be tested in the LHC-b and B factories in the near future.