Observation of $B_{s}^{0} \to \mu ^{+} \mu ^{-}$ at CMS and LHCb and Future Plans at LHCb

The branching fractions of the decays $B^{0} \to \mu^{+} \mu^{-}$ and $B_{s}^{0} \to \mu^{+} \mu^{-}$ are highly suppressed in the Standard Model but can be modified by contributions from new physics models. The combined result from the CMS and LHCb Run 1 data for the $B^{0} \to \mu^{+} \mu^{-}$ and $B_{s}^{0} \to \mu^{+} \mu^{-}$ branching fractions is presented here. The measured results are $\mathcal{B}(B_{s}^{0} \to \mu^{+} \mu^{-}) = (2.8^{+0.7}_{-0.6})\times 10^{-9}$ at $6.2 \sigma$ statistical significance and $\mathcal{B}(B^{0} \to \mu^{+} \mu^{-}) = (3.9^{+1.6}_{-1.4})\times 10^{-10}$ at $3.0 \sigma$ statistical significance, both results are consistent with Standard Model predictions. A brief discussion of the future prospects for the study of $B^{0} \to \mu^{+} \mu^{-}$ and $B_{s}^{0} \to \mu^{+} \mu^{-}$ at the LHCb is also included.