We study Bmeson decays to D final states using a sample of 657 10B B events collected at
the 4S resonance with the Belle detector at the KEKB asymmetric-energy eþecollider. The observed
branching fraction for B Dis 1 43
018 10 with a significance of 8.1 standard
deviations, where the uncertainties are statistical and systematic, respectively. Most of the signal events
have the mass peaking near threshold.