Observation of $B^{\pm }\to D_{CP}{K}^{\ast \pm }$ Decays

Abstract

We report preliminary results on the decay $B^{-}\to D^0{K}^{\ast -}$, $B^{-}\to D_{CP}{K}^{\ast -}$ and its charge c onjugate using a data sample of 95.8 million $B\bar{B}$ pairs recorded at the ${\rm Y}(4S)$ resonance with the Belle d etector at the KEKB asymmetric $e^{+}{e}^{-}$ storage ring. We find the branching fraction for $B^{-}\to D^0{K}^{\ast -}$ to be $\mathcal{B}=(5.2\pm 0.5(stat)\pm 0.6(sys))\times 10^{-4}$ and the partial-rate charge asymmetries for $B^{-} \rig htarrow D_{CP}K^{*-}$ to be ${\mathcal{A}}_1=-0.02\pm 0.33(stat)\pm 0.07(sys)$ and ${\mathcal{A}}_2=0.19\pm 0.50(stat)\pm 0.04(sys)$ where the indices 1 and 2 represent the CP=+1 and CP=$-$1 eigenstates of the $D^0-\overline{D^0}$ system, respectively .

9 pages, 2 figures, submitted to 2003 International Europhysics Conference on High Energy Physics and XXI International Symposium on Lepton and Photon Interactions at High Energies