Search for b -> u transitions in B(-) -> DK(-) and D*K(-) decays RID C-5223-2009

We report results from an updated study of the suppressed decays We report results from an updated study of the suppressed decays B(-) -> DK(-) and B(-) -> D*K(-) followed by D -> K(+) pi(-), where D(()*()0) indicates a D(()*()0)or a (D) over bar (()*()0) meson, and D* -> D pi(0) or D* -> D gamma. These decays are sensitive to the Cabibbo-Kobayashi-Maskawa unitarity triangle angle gamma due to interference between the b -> c transition B(-) -> D(()*()0)K(-) followed by the doubly Cabibbo-suppressed decay D(0) -> K(+) pi(-), and the b -> u transition B(-) -> (D) over bar (()*()0) K(-) followed by the Cabibbo-favored decay (D) over bar (0) -> K(+) pi(-). We also report an analysis of the decay B(-) -> D(()*())pi(-) with the D decaying into the doubly Cabibbo-suppressed mode D -> K(+) pi(-). Our results are based on 467 x 10(6) Gamma(4S) -> BB(-) decays collected with the BABAR detector at SLAC. We measure the ratios R(()*()) of the suppressed ([K(+) pi(-)](D)K(-) / pi(-)) to favored ([K(+) pi(-)](D)K(-) / pi(-)) branching fractions as well as the CP asymmetries A(()*()) of those modes. We see indications of signals for the B(-) -> DK(-) and B(-) -> D(D pi 0)(()*()) K(-) suppressed modes, with statistical significances of 2.1 and 2.2 sigma, respectively, and we measure: R(DK) = (1.1 +/- 0: 6 +/- 0.2) x 10(-2); A(DK) = -0.86 +/- 0: 47(-0.16)(+0.12), R((D pi 0)K)* = (1.8 +/- 0: 9 +/- 0: 4) x 10(-2); A ((D pi 0)K)* = +0.77 +/- 0: 35 +/- 0.12; R((D gamma)K)* = (1.3 +/- 1.4 +/- 0.8) x 10(-2); A((D gamma)K)* = +0.36 +/- 0: 94(-0.41)(+0.25), where the first uncertainty is statistical and the second is systematic. We use a frequentist approach to obtain the magnitude of the ratio r(B) equivalent to vertical bar A(B(-) -> (D) over bar 0K(-))/A(B(-) -> D(0)K(-))vertical bar = (9.5(-4.1)(+5.1))%, with r(B) < 16: 7% at 90% confidence level. In the case of B(-) -> D*K(-) we find r(B) equivalent to vertical bar A(B(-) -> <(D)over bar>0K(-))/A(B(-) -> D(0)K(-))vertical bar = (9.6(-5.1)(+3.5))%, with r(B)* < 15.0% at 90% confidence level.