Measurement of the branching fraction and charge asymmetry of the decay B+→D+(D)over-bar0 and search for B0→D0(D)over-bar0

We report an improved measurement of the B+-> D+(D) over bar (0) and B-0 -> D-0(D) over bar (0) decays based on 657 x 10(6) B (B) over bar events collected with the Belle detector at KEKB. We measure the branching fraction and charge asymmetry for the B+-> D+(D) over bar (0) decay: B(B+-> D+(D) over bar (0)) = (3.85 +/- 0.31 +/- 0.38) x 10(-4) and A(CP)(B+-> D+(D) over bar (0))= 0.00 +/- 0.08 +/- 0.02, where the first error is statistical and the second is systematic. We also set the upper limit for the B-0 -> D-0(D) over bar (0) decay: B(B-0 -> D-0(D) over bar (0)) < 0.43 x 10(-4) at 90% CL.