Search for b-> u transitions in B0 -> D0 K*0 decays

TL;DR

This paper investigates B0 decays to D0 K*0 to measure the ratio of b->u to b->c transition amplitudes, setting upper limits on decay ratios and constraining the amplitude ratio rS.

Contribution

The study provides new experimental limits on decay ratios and constrains the amplitude ratio rS in B0 decays, using a large dataset from the BaBar detector.

Findings

No significant signal observed for the decay ratios.

Upper limits set on R_{ADS} for three decay modes.

The amplitude ratio rS is constrained to be between 0.07 and 0.41 at 95% probability.

Abstract

We present a study of the decays B0 -> D0 K*0 and B0 -> barD0 K*0 with K*0 -> K+pi-. The D0 and the barD0 mesons are reconstructed in the final states f=K+pi-, K+pi-pi0, K+pi-pi+pi- and their charge conjugates. Using a sample of 465 million BBbar pairs collected with the Babar detector at the PEP-II asymmetric-energy e+e- collider at SLAC, we measure the ratio R_{ADS}=[Gamma(barB0 -> [f]_D barK*0)+Gamma(B0 -> [bar{f}]_D K*0)]/ [Gamma(barB0 -> [bar{f}]_D barK*0)+Gamma(B0 -> [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}(Kpi)<0.244, R_{ADS}(Kpipi0)<0.181 and R_{ADS}(Kpipipi)<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.