Search for Bs0→μ+μ- and B0→μ+μ- decays with the full CDF Run II data set

We report on a search for smm and dmm decays using proton-antiproton collision data at s√=1.96 TeV corresponding to $10 b$ of integrated luminosity collected by the CDF detector at the Fermilab Tevatron collider. The observed number of d candidates is consistent with background-only expectations and yields an upper limit on the branching fraction of $rbdmm < 4.6 imes 10^{-9}$ at 95% confidence level. We observe an excess of s candidates. The probability that the background processes alone could produce such an excess or larger is 0.94%. The probability that the combination of background and the expected standard model rate of smm could produce such an excess or larger is 6.8%. These data are used to determine a branching fraction $rbsmm = (1.3^{+0.9}_{-0.7}) imes 10^{-8}$ and provide an upper limit of $rbsmm < 3.1 imes 10^{-8}$ at 95% confidence level.