Evidence for B0 --D+ D- and observation of B- --D0D- and B- --D0D*- decays

We report evidence for B(0) --D(0)D(-) and the first observation of the decay modes B(-) --D(0)D(-) and B(-) --D(0)D(*-) based on a sample of 152 x 10(6) BB events collected by the Belle detector at KEKB. The branching fractions for B(0) --D(+) D(-), B---D(0)D(-), and B--D(0)D(*-) are found to be (1.91 +/- 0.51 +/- 0.30) x10(-4), (4.83 +/- 0.78 +/- 0.58) x 10(-4), and (4.57 +/- 0.71 +/- 0.56) x 10(-4), respectively. Charge asymmetries in the B---D(0)D(-) and B(-) --D(0)D(*-) channels are consistent with zero.