Measurement of branching fraction ratios and CP asymmetries in B ±→D;CPK±

We report results on the decay B- → DCPK - and its charge conjugate using a data sample of 85.4 × 106 BB̄ pairs recorded at the γ(4S) resonance with the Belle detector at the KEKB asymmetric e+e- storage ring. Ratios of branching fractions of Cabibbo-suppressed to Cabibbo-favored processes are determined to be Β(B- → D0K -)/Β(B- → D0 π-) = 0.077±0.005(stat)±0.006(syst), Β(B- → D 1K-)/Β(B- → D1π - = 0.093 ±0.018(stat)±0.008(syst) and Β(B - → D2K-)/Β(B- → D2 π-) = 0-108±0.019(stat)±0.007(syst) where the indices 1 and 2 represent the CP= + 1 and CP= - 1 eigenstates of the D0-D̄0 system, respectively. We find the partial-rate charge asymmetries for B- → DCPK- to be A1 =0.06±0.19(stat)±0.04(syst) and A2 = -0.19±0.17(stat)±0.05(syst). © 2003 The American Physical Society.