Search for Bs,B0->mumu decays at CMS

Results were presented from a search for the rare decays B s → μ + μ − and B 0 → μ + μ − in pp collisions at √ s = 7 and 8 TeV, with data samples corresponding to integrated l uminosities of 5 and 20 fb − 1 , respectively, collected by the CMS experiment at the LHC. A n unbinned maximum-likelihood fit to the dimuon invariant mass distrib ution gives a branching fraction B ( B s → μ + μ − ) = ( 3 . 0 + 1 . 0 − 0 . 9 ) × 10 − 9 , where the uncertainty includes both statistical and syste m- atic contributions. An excess of B s → μ + μ − events with respect to background is observed with a significance of 4.3 standard deviations. The expected medi an significance of this excess is 4.8 standard deviations. For the decay B 0 → μ + μ − an upper limit of B ( B 0 → μ + μ − ) < 1 . 1 × 10 − 9 at the 95% confidence level is determined. Both results are in agreement with the expectations from the standard model