Friday, July 19, 2013

1307.5025 (CMS Collaboration)

Measurement of the Bs to mu mu branching fraction and search for B0 to
mu mu with the CMS Experiment

CMS Collaboration
Results are presented from a search for the rare decays Bs to mu mu and B0 to mu mu in pp collisions at sqrt(s)=7 and 8 TeV, with data samples corresponding to integrated luminosities of 5 and 20 inverse femtobarns, respectively, collected by the CMS experiment at the LHC. An unbinned maximum-likelihood fit to the dimuon invariant mass distribution gives a branching fraction B(Bs to mu mu) = (3 +1.0/-0.9)E-9, where the uncertainty includes both statistical and systematic contributions. An excess of Bs to mu mu events with respect to background is observed with a significance of 4.3 standard deviations. For the decay B0 to mu mu an upper limit of B(B0 to mu mu) < 1.1E-9 at the 95% confidence level is determined. Both results are in agreement with the expectations from the standard model.
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