Improved measurement of CP observables in B(+/-)-> DCP(0)K(+/-) decays RID C-5223-2009 RID C-5719-2008

We present a study of the decay B(-)-> D((CP))(0)K(-) and its charge conjugate, where D((CP))(0) is reconstructed in both a non-CP flavor eigenstate and in CP (CP-even and CP-odd) eigenstates, based on a sample of 382 million Upsilon(4S) -> B (B) over bar decays collected with the BABAR detector at the PEP-II e(+)e(-) storage ring. We measure the direct CP asymmetries A(CP +/-) and the ratios of the branching fractions R(CP +/-): A(CP+)=0.27 +/- 0.09(stat) +/- 0.04(syst), A(CP-)=-0.09 +/- 0.09(stat) +/- 0.02(syst), R(CP+)=1.06 +/- 0.10(stat) +/- 0.05(syst), R(CP-)=1.03 +/- 0.10(stat) +/- 0.05(syst). We also express the results in terms of the so-called Cartesian coordinates x(+), x(-), and r(2): x(+)=-0.09 +/- 0.05(stat) +/- 0.02(syst), x(-)=0.10 +/- 0.05(stat) +/- 0.03(syst), r(2)=0.05 +/- 0.07(stat)+/- 0.03(syst). These results will help to better constrain the phase parameter gamma=arg(-V(ud)V(ub)(*)/V(cd)V(cb)(*)) of the Cabibbo-Kobayashi-Maskawa quark mixing matrix.