Abstract:

We report a preliminary measurement of the ratio of the branching fractions: , using data taken with the CLEO III detector at the resonance. We also discuss recent progress on the attempt to measure their distributions. These measurements are of interest because they have the potential to discriminate among nonperturbative semileptonic form factors, thus providing experimental checks for the theoretical techniques employed in their calculation. The hope is that this will ultimately improve precision measurements of the CKM matrix, and in particular, exclusive measurements of .