Accepted Thursday Nov 05, 2009
We present measurements of the branching fraction and longitudinal polarization fraction for decays, with . The data sample, collected with the detector at the SLAC National Accelerator Laboratory, represents 465 ×106 produced pairs. We measure \BrBapam ×[\Braunop ]2 = \RapamP and \fL = 0.31 0.22 0.10, where the first uncertainty is statistical and the second systematic. The decay mode is measured with a significance of 5.0 standard deviations including systematic uncertainties.