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 $\left( 2.69\,^{+\, 0.37}_{-\, 0.35} \right) \times 10^{-9}$ and the effective lifetime of the $B^0_{s} \to \mu^+ \mu^-$ decay is measured to be $\tau_{B^0_{s} \to \mu^+ \mu^-} = 1.91^{+0.37}_{-0.35} \rm{ps}$. 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.