Measurement of CP-Asymmetries for the Decays B+/- to D_cp Kstar+/- with the BABAR Detector

Abstract

Using a sample of 227 million $\hat{I}\yen (4S)\to B\bar{B}$ events collected with the $BABAR$ detector at the PEP-II $B$ Factory in 1999--2004, we study $B^{-}\to D^0{K}^{\ast }(892{)}^{-}$ decays where $K^{\ast -}\to K_S^0\ddot{I}{€}^{-}$ and $D^0\to K^{-}\ddot{I}{€}^{+},K^{-}\ddot{I}{€}^{+}\ddot{I}{€}^0,K^{-}\ddot{I}{€}^{+}\ddot{I}{€}^{+}\ddot{I}{€}^{-}$ (non-CP final states), $K^{+}{K}^{-},\ddot{I}{€}^{+}\ddot{I}{€}^{-}(CP+$ eigenstates), $K_S^0\ddot{I}{€}^0,K_S^0\ddot{I}•$ and $K_S^0\ddot{I}‰(CP-$ eigenstates). The partial rate charge asymmetries ${\mathcal{A}}_{CP}$ and the ratios ${\mathcal{R}}_{CP}$ defined in the literature as the sum of the $B^{+}$ and $B^{-}$ partial rates to a charged $K^{\ast }$ and a $D^{0}CP$-eigenstate divi ded by the $B\to D^0{K}^{\ast }$ decay rate, %of the \ensuremath{\Bu}\xspace\xspace m \ensuremath{\to}\xspace \Dcp \ensuremath{K^*}\xspacepm branch ing fractions summed over %\B charge to the \ensuremath{B^-}\xspace \xspace\ensuremath{\to}\xspace \ensuremath{D^0}\xspace \ensu remath{K^{*-}}\xspace branching fraction are sensitive to the angle ${\hat{I}}^3$ of the CKM unitarity triangle. We measure: \mathcal{A}_{CP+} &=&-0.09 \pm 0.20 (stat.) \pm 0.06 (syst.) \mathcal{A}_{CP-} &=& -0.33 \pm 0.34 (stat.) \pm 0.10 (syst.) (+1.15 \pm 0.12) \cdot (\mathcal{A}_{CP-} - \mathcal{A}_{CP+}) \mathcal{R}_{CP+} &=& +1.77 \pm 0.37 (stat.) \pm 0.12 (syst.) \mathcal{R}_{CP-} &=& +0.76 \pm 0.29 (stat.) \pm 0.06 (syst.) ^{- 0.04}_{-\ 0.14} The third uncertainty quoted for the CP- measurements reflects possible interference effects in the final states with $\ddot{I}•$ and $\ddot{I}‰$ resonances. All results are preliminary.

Contributed to ICHEP 2004 in Beijing