Search for the 𝐵�0𝑠� → μ+μ−γ decay

Abstract

A search for the fully reconstructed 𝐵0𝑠 → μ+μ−γ decay is performed at the LHCb experiment using proton-proton collisions at 𝑠√ = 13 TeV corresponding to an integrated luminosity of 5.4 fb−1. No significant signal is found and upper limits on the branching fraction in intervals of the dimuon mass are set

(𝐵0𝑠→𝜇+𝜇−𝛾)<4.2×10−8,(𝐵0𝑠→𝜇+𝜇−𝛾)<7.7×10−8,(𝐵0𝑠→𝜇+𝜇−𝛾)<4.2×10−8,𝑚(𝜇+𝜇−)∈[2𝑚𝜇,1.70]GeV/𝑐2, 𝑚(𝜇+𝜇−)∈[1.70,2.88]GeV/𝑐2,𝑚(𝜇+𝜇−)∈[3.92,𝑚𝐵0𝑠]GeV/𝑐2, at 95% confidence level. Additionally, upper limits are set on the branching fraction in the [2mμ, 1.70] GeV/c2 dimuon mass region excluding the contribution from the intermediate ϕ(1020) meson, and in the region combining all dimuon-mass intervals.