Search for $B_s \rightarrow \mu^{+}\mu^{-}$ and $B_d \rightarrow \mu^{+}\mu^{-}$ decays with the full CDF Run II data set

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We report on a search for \bsmm\ and \bdmm\ decays using proton-antiproton collision data at $\sqrt{s}=1.96$ TeV corresponding to $10 \fb$ of integrated luminosity collected by the CDF detector at the Fermilab Tevatron collider.

• The observed number of \bd\ candidates is consistent with background-only expectations and yields an upper limit on the branching fraction of $\brbdmm < 4.6\times 10^{-9}$ at 95% confidence level.
• We observe an excess of \bs\ candidates.
• The probability that the background processes alone could produce such an excess or larger is 0.94%.