Measurement of B0bar -> D(*)0 K(*)0bar Branching Fractions
  We present a study of the decays B0bar --> D(*)0 K(*)0bar using a sample of 226 million Y(4S) --> B Bbar decays collected with the BaBar detector at the PEP-II asymmetric-energy e+e-collider at SLAC. We report evidence for the decay of B0 and B0bar mesons to the D*0 K0s final state with an average branching fraction BF(B0-tilde --> D*0 K0bar) := [ BF(B0bar --> D*0 K0bar) + BF(B0 --> D*0 K0) ]/2 = (3.6 +- 1.2 +- 0.3) x 10^-5. Similarly, we measure BF(B0-tilde --> D0 K0bar) := [ BF(B0bar --> D0 K0bar) + BF(B0 --> D0 K0) ]/2 = (5.3 +- 0.7 +- 0.3) x 10^-5 forthe D0 K0s final state. We measure BF(B0bar --> D0 K*0bar) =^(4.0 +- 0.7 +- 0.3) x 10^-5 and set a 90% confidence level upper limit BF(B0bar --> D0bar K*0bar) < 1.1 x 10^-5. We determine the upper limit for the decay amplitude ratio |A(B0bar --> D0bar K*0bar)/A(B0bar --> D0 K*0bar)| to be less than 0.4 at the 90% confidence level. 
The BABAR Collaboration, B. Aubert, et al