Search for b→u transitions in B0→D0K*0 decays

We present a study of the decays B 0 → D 0 K * 0 and B 0 → ¯¯¯ D 0 K * 0 with K * 0 → K + π − . The D 0 and the ¯¯¯ D 0 mesons are reconstructed in the final states f = K + π − , K + π − π 0 , K + π − π + π − , and their charge conjugates. Using a sample of 465 × 10 6 B ¯¯¯ B pairs collected with the BABAR detector at the PEP-II asymmetric-energy e + e − collider at SLAC, we measure the ratio R ADS ≡ [ Γ ( ¯¯¯ B 0 → [ f ] D ¯¯¯¯ K * 0 ) + Γ ( B 0 → [ ¯ f ] D K * 0 ) ] / [ Γ ( ¯¯¯ B 0 → [ ¯ f ] D ¯¯¯¯ K * 0 ) + Γ ( B 0 → [ f ] D K * 0 ) ] for the three final states. We do not find significant evidence for a signal and set the following limits at 95% probability: R ADS ( K π ) < 0.244 , R ADS ( K π π 0 ) < 0.181 , and R ADS ( K π π π ) < 0.391 . From the combination of these three results, we find that the ratio r S between the b → u and the b → c amplitudes lies in the range [0.07,0.41] at 95% probability