Search for $B_s^0\to {\mu }^{+}{\mu }^{-}$ and $B^0\to {\mu }^{+}{\mu }^{-}$ Decays with $2{\mathrm{fb}}^{-1}$ of $p\overline{p}$ Collisions

We have performed a search for $B_s^0\to {\mu }^{+}{\mu }^{-}$ and $B^0\to {\mu }^{+}{\mu }^{-}$ decays in $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$ using $2{\mathrm{fb}}^{-1}$ of integrated luminosity collected by the CDF II detector at the Fermilab Tevatron Collider. The observed number of $B_s^0$ and $B^0$ candidates is consistent with background expectations. The resulting upper limits on the branching fractions are $\mathcal{B}(B_s^0\to {\mu }^{+}{\mu }^{-})<5.8\times {10}^{-8}$ and $\mathcal{B}(B^0\to {\mu }^{+}{\mu }^{-})<1.8\times {10}^{-8}$ at 95% C.L.

Figure 1

Distributions of ${\nu }_N$ for simulated $B_s^0\to {\mu }^{+}{\mu }^{-}$ signal and observed sideband events.

Figure 2

The ${\mu }^{+}{\mu }^{-}$ invariant mass distribution for events satisfying all selection criteria for the final three ranges of ${\nu }_N$.