The decays of the B⁰ and the B_s mesons to muon pairs (μμ) are highly suppressed in the Standard Model. A measurement of the branching fraction for either of these decays that is inconsistent with the model’s prediction would be a clear sign of new physics. For the past 30 years, a dozen experiments at nearly as many particle colliders have looked for these elusive decays. Last November, LHCb found the first clear evidence for the decay B_s → μμ, at the 3.5 sigma level. Now both the CMS and LHCb collaborations have updated their results for these decays.

Read more: "Strangely beautiful dimuons" – CERN Courier