Combination of the ATLAS, CMS and LHCb results on the $B^0_{(s)} \to \mu^+\mu^-$ decays

A combination of results on the rare $B^0_s \to \mu^+\mu^-$ and $B^0 \to \mu^+\mu^-$ decays from the ATLAS, CMS, and LHCb experiments using data collected at the Large Hadron Collider between 2011 and 2016, is presented. The $B^0_s \to \mu^+\mu^-$ branching fraction is obtained to be $(2.69\,^{+\, 0.37}_{-\, 0.35}) \times 10^{-9}$ and the effective lifetime of the $B^0_s \to \mu^+\mu^-$ decay is measured to be $\tau_{B^0_s \to \mu^+\mu^-} = 1.91^{+0.37}_{-0.35}$ ps. An upper limit on the $B^0 \to \mu^+\mu^-$ branching fraction is evaluated to be $\mathcal{B}(B^0 \to \mu^+\mu^-) < 1.6~(1.9)\times 10^{-10}$ at $90\%$ ($95\%$) confidence level. An upper limit on the ratio of the $B^0 \to \mu^+\mu^-$ and $B^0_s \to \mu^+\mu^-$ branching fractions is obtained to be $0.052~(0.060)$ at $90\%$ ($95\%$) confidence level.