Production and decay properties of the ωπ0state at 1250 MeV/c2produced by 20-GeV polarized photons on hydrogen

The low-mass ω${\pi }^0$ enhancement in γp→pω${\pi }^0$ has been of considerable interest in the past due to its suggested vector nature and possible role in the spectroscopy of the ρ-meson radial recurrences. We have measured the properties of this photoproduced ω${\pi }^0$ system using the SLAC Hybrid Facility. The experimental data consists of 306 785 usable hadronic events for which excellent γ-ray detection is provided by the large lead-glass array located behind the bubble-chamber. The photon beam had a 52% polarization. We have examined in detail the angular distributions of the 274 events from the reaction γp→pω${\pi }^0$. The angular distribution of the production plane relative to the polarization vector shows a structure inconsistent with an s-channel helicity-conserving process. We have extracted the moments of the decay angular distribution. Our data favors a B(1235) interpretation of the ω${\pi }^0$ state over a vector-meson interpretation.