Search for color-suppressed $B$ hadronic decay processes at the ${\rm Y}\mathrm{}\left(4S\right)\mathrm{}$ resonance

Using $3.1{\mathrm{fb}}^{\mathrm{-}1}$ of data accumulated at the ${\rm Y}\mathrm{}\left(4S\right)\mathrm{}$ by the CLEO-II detector, corresponding to $3.3\times {10}^6$ $B\overline{B}$ pairs, we have searched for the color-suppressed $B$ hadronic decay processes $B^0\to D^0{(D}^{*0}){\mathrm{X}}^0,$ where ${\mathrm{X}}^0$ is a light neutral meson ${\pi }^0,$ ${\rho }^0,$ η, ${\eta }^{\prime }$ or ω. The $D^{*0}$ mesons are reconstructed in $D^{*0}\to D^0{\pi }^0$ and the $D^0$ mesons in $D^0\to K^{-}{\pi }^{+},$ $K^{-}{\pi }^{+}{\pi }^0$ and $K^{-}{\pi }^{+}{\pi }^{+}{\pi }^{-}$ decay modes. No obvious signal is observed. We set 90% C.L. upper limits on these modes, varying from $1.2\times {10}^{-4}$ for $B^0\to D^0{\pi }^0$ to $1.9\times {10}^{-3}$ for $B^0\to D^{*0}{\eta }^{\prime }.$