Search forBs0→μ+μ−andBd0→μ+μ−Decays inpp¯Collisions with CDF II

We report on a search for ${B}_{s}^{0}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ and ${B}_{d}^{0}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}}$ decays in $p\overline{p}$ collisions at $\sqrt{s}=1.96\text{ }\text{ }\mathrm{TeV}$ using $364\text{ }{\mathrm{pb}}^{\ensuremath{-}1}$ of data collected by the CDF II detector at the Fermilab Tevatron Collider. After applying all selection requirements, we observe no candidates inside the ${B}_{s}^{0}$ or ${B}_{d}^{0}$ mass windows. The resulting upper limits on the branching fractions are $\mathcal{B}({B}_{s}^{0}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}})l1.5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}7}$ and $\mathcal{B}({B}_{d}^{0}\ensuremath{\rightarrow}{\ensuremath{\mu}}^{+}{\ensuremath{\mu}}^{\ensuremath{-}})l3.9\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}8}$ at 90% confidence level.