Abstract
Photoproduction is studied at 2.8 and 4.7 GeV using a linearly polarized monoenergetic photon beam in a hydrogen bubble chamber. We discuss the experimental procedure, the determination of channel cross sections, and the analysis of the channel . A model-independent analysis of the -decay angular distribution allows us to measure nine independent density-matrix elements. From these we find that the reaction proceeds almost completely through natural parity exchange for squared momentum transfers Ge and that the production mechanism is consistent with -channel c.m. helicity conservation for Ge. A cross section for the production of pairs in the -channel c.m. helicity-conserving -wave state is determined. The mass shape is studied as a function of momentum transfer and is found to be inconsistent with a -independent Ross-Stodolsky factor. Using a -dependent parametrization of the mass shape we derive a phenomenological cross section. We compare our phenomenological cross section with other experiments and find good agreement for Ge. We discuss the discrepancies in the various determinations of the forward differential cross section. We study models for photoproduction and find that the Söding model best describes the data. Using the Söding model we determine a cross section. We determine cross sections and nine density-matrix elements for . The parity asymmetry for production is incompatible with simple one-pion exchange. We compare production with models.
- Received 2 August 1971
DOI:https://doi.org/10.1103/PhysRevD.5.545
©1972 American Physical Society