Abstract
Results are presented from a search for the rare decays and in collisions at and 8 TeV, with data samples corresponding to integrated luminosities of 5 and , respectively, collected by the CMS experiment at the LHC. An unbinned maximum-likelihood fit to the dimuon invariant mass distribution gives a branching fraction , where the uncertainty includes both statistical and systematic contributions. An excess of events with respect to background is observed with a significance of 4.3 standard deviations. For the decay an upper limit of at the 95% confidence level is determined. Both results are in agreement with the expectations from the standard model.
- Received 18 July 2013
DOI:https://doi.org/10.1103/PhysRevLett.111.101804
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© 2013 CERN, for the CMS Collaboration