Observation of Exclusive Bbar --> D(*)K*- Decays

We report the first observation of the exclusive decays Bbar-->D^(*)K^*-, using 9.66×10⁶ BBbar pairs collected at the ϒ(4S) with the CLEO detector. We measure the following branching fractions: B(B^--->D⁰K^*-) = (6.1+/-1.6+/-1.7)×10^-4, B(Bbar⁰-->D⁺K^*-) = (3.7+/-1.5+/-1.0)×10^-4, B(Bbar⁰-->D^*+K^*-) = (3.8+/-1.3+/-0.8)×10^-4, and B(B^--->D^*0K^*-) = (7.7+/-2.2+/-2.6)×10^-4. The Bbar-->D^*K^*- branching ratios are the averages of those corresponding to the 00 and 11 helicity states. The errors shown are statistical and systematic, respectively.