in the continuum at 60 MeV less center-of-mass energy. The sample contains 19.4 million $B$ mesons.

Common Selection Criteria {#sec:Common}
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Hadronic events are selected by a minimum of five charged tracks, total visible energy greater than 15% of the center-of-mass energy, and a charged track vertex consistent with the nominal interaction point. To reject continuum we require that the Fox-Wolfram moment $R_2$ be less than 0.3 [@Fox-Wolf].

Track candidates are required to pass through a common spatial point defined by origin of all tracks. Tracks with momentum below 900 MeV/c are required to have ionization loss in the drift chamber within $3\sigma$ of their assigned mass.[^3] (These requirements are not imposed on slow charged pions from $D^{*+}$ decay.) Photon candidates are required to be within the “good barrel region," within 45$^{\circ}$ of the normal to the beam line, and have an energy distribution in the CsI calorimeter consistent with that of an electromagnetic shower. To select $\pi^o$’s, we require that the diphoton invariant mass be between -3.0 to +2.5$\sigma$, where $\sigma$ varies with momentum and has an average value of approximately 5.5 MeV. For each two-photon mass combination $\sigma$ is calculated. After candidate selection the two-photon’s are kinematically fit 