Search for the rare decay $B_s^0\to \varphi {\mu }^{+}{\mu }^{-}$ with the D0 detector

We present a search for the flavor-changing neutral current decay $B_s^0\to \varphi {\mu }^{+}{\mu }^{-}$ using about $0.45{\mathrm{fb}}^{-1}$ of data collected in $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$ with the D0 detector at the Fermilab Tevatron Collider. We find an upper limit on the branching ratio of this decay normalized to $B_s^0\to J/\psi \varphi$ of $\frac{\mathcal{B}(B_s^0\to \varphi {\mu }^{+}{\mu }^{-})}{\mathcal{B}(B_s^0\to J/\psi \varphi )}<4.4\times {10}^{-3}$ at the 95% C.L. Using the central value of the world average branching fraction of $B_s^0\to J/\psi \varphi$, the limit corresponds to $\mathcal{B}(B_s^0\to \varphi {\mu }^{+}{\mu }^{-})<4.1\times {10}^{-6}$ at the 95% C.L., the most stringent upper bound to date.

Figure 1

The invariant mass distribution after optimized requirements on the discriminating variables. The solid line shows the sidebands background interpolation into the signal region.

Figure 2

The invariant mass distribution of the normalization channel $B_s^0\to J/\psi \varphi$ after all selection criteria.