Observation of $B_s^0\to \psi (2S)\varphi$ and Measurement of the Ratio of Branching Fractions $\mathcal{B}\mathbf{(}{B}_s^0\to \psi (2S)\varphi \mathbf{)}/\mathcal{B}(B_s^0\to J/\psi \varphi )$

We report the first observation of $B_s^0\to \psi (2S)\varphi$ decay in $p\overline{p}$ collisions at $\sqrt{s}=1.96\mathrm{TeV}$ using $360{\mathrm{pb}}^{-1}$ of data collected by the CDF II detector at the Fermilab Tevatron. We observe $20.2\pm 5.0$ and $12.3\pm 4.1$ $B_s^0\to \psi (2S)\varphi$ candidates, in $\psi (2S)\to {\mu }^{+}{\mu }^{-}$ and $\psi (2S)\to J/\psi {\pi }^{+}{\pi }^{-}$ decay modes, respectively. We present a measurement of the relative branching fraction $\mathcal{B}\mathbf{(}{B}_s^0\to \psi (2S)\varphi \mathbf{)}/\mathcal{B}(B_s^0\to J/\psi \varphi )=0.52\pm 0.13(\mathrm{stat})\pm 0.04(\mathrm{syst})\pm 0.06(\mathrm{BR})$ using the $\psi (2S)\to {\mu }^{+}{\mu }^{-}$ decay mode.

Figure 1

Tree-level Feynman diagram of $B$ mesons decaying to charmonium final states.

Figure 2

Invariant mass distributions for $B_s^0\to J/\psi \varphi$ (bottom), and for $B_s^0\to \psi (2S)\varphi$, followed by $\psi (2S)\to {\mu }^{+}{\mu }^{-}$ (upper left), or $\psi (2S)\to J/\psi {\pi }^{+}{\pi }^{-}$ (upper right). The curves are the results of the fits described in the text.