Bs0→μ+μ−γ from Bs0→μ+μ−

The Bs0→μ+μ−γ decay offers sensitivity to a wider set of effective operators than its non-radiative counterpart Bs0→μ+μ−, and a set that is interesting in the light of present-day discrepancies in flavour data. On the other hand, the direct measurement of the Bs0→μ+μ−γ decay poses challenges with respect to the Bs0→μ+μ− one. We present a novel strategy to search for Bs0→μ+μ−γ decays in the very event sample selected for Bs0→μ+μ− searches. The method consists in extracting the Bs0→μ+μ−γ spectrum as a “contamination” to the Bs0→μ+μ− one, as the signal window for the latter is extended downward with respect to the peak region. We provide arguments for the actual practicability of the method already on Run 2 data of the LHC.