The use of early data on B --> rho pi decays

Abstract

This paper reviews the Dalitz plot analysis for the decays $B^0(\bar B^0) \to ρπ\to π^+ π^- π^0$. We discuss what can be learned about the ten parameters in this analysis from untagged and from tagged time-integrated data. We find that, with the important exception of the interesting CP violating quantity $α$, the parameters can be determined from this data sample -- and, hence, they can be measured at CLEO as well as at the asymmetric $B$ factories. This suggests that the extraction of $α$ from the time-dependent data sample can be accomplished with a smaller data sample (and, therefore, sooner) than would be required if all ten parameters were to be obtained from that time-dependent data sample alone. We also explore bounds on the shift of the true angle $α$ from the angle measured from charged $ρ$ final states alone. These may be obtained prior to measurements of the parameters describing the neutral $ρ$ channel, which are expected to be small.