Search for b → u Transitions in B0 → D0 K*0 Decays

We present a study of the decays B0 → D0 K*0 and B0 → (bar D)0 K*0 with K*0 → K+π-. The D0 and the (bar D)0 mesons are reconstructed in the final states f = K+ π-, K+π-π0, K+π-π+π- and their charge conjugates. Using a sample of 465 million B(bar B) pairs collected with the BABAR detector at PEP-II asymmetric-energy e+e- collider at SLAC, we measure the ratio RADS (triplebond) [Λ((bar B)0 → [f]D(bar K)*0) + Λ(B0 → [(bar f)]DK*0)]/[Λ((bar B)0 → [(bar f)]D(bar K)*0) + Λ(B0 → [f]DK*0)] for the three final states. We do not find significant evidence for a signal and set the following limits at 95% probability: RADS(Kπ) < 0.244, RADS(Kππ0) < 0.181 and RADS(Kπππ) < 0.391. From the combination of these three results, we find that the ratio rS between the b → u and the b → c amplitudes lies in the range [0.07; 0.41] at 95% probability