Reconstruction ofB0→J/ψKS0and Measurement of Ratios of Branching Ratios InvolvingB→J/ψK*andB+→J/ψK+

We report on the reconstruction of the decay mode $B^0\to J/\psi K_S^0$ using $19.3{\mathrm{pb}}^{-1\mathrm{}}$ of data collected by the Collider Detector at Fermilab in $\overline{p}p$ collisions at $\sqrt{s}=1.8\mathrm{}\mathrm{TeV}$. A signal of $41.8\pm 6.9$ events, with a signal-to-background ratio of $9:1$, is observed. Three additional decay modes $B^{+}\to J/\psi K^{+}$, $B^0\to J/\psi K^{*}(892{)}^0$, and $B^{+}\to J/\psi K^{*}(892{)}^{+}$ are reconstructed. We measure three ratios of branching ratios, each one relative to the $B^{+}\to J/\psi K^{+}$ mode. We also report the ratio of decay rates, $\gamma (B\to J/\psi K^{*})/\gamma (B\to J/\psi K)$, for the vector-vector relative to the vector-pseudoscalar modes, to be $1.32\pm 0.23\left(\mathrm{stat}\right)\pm 0.16\left(\mathrm{syst}\right)$.