Analyzing Η Photoproduction Data on the Proton at Energies of 1.5–2.3 Gev

One of the primary interests in investigating η meson-production reactions is that they may be suited to extract information on nucleon resonances, N, in the less-explored higher N mass region. Current knowledge of most of the nucleon resonances is mainly due to the study of πN scattering and/or pion photoproduction off the nucleon. Since the η meson is much heavier than a pion, η meson-production processes near threshold necessarily sample a much higher resonance-mass region than the corresponding pion production processes. Therefore, they are well-suited for investigating high-mass resonances in low partial-wave states. Furthermore, these reactions provide opportunities to study those resonances that couple only weakly to pions, in particular, those referred to as “missing resonances”. Another special interest in η photoproduction is the possibility to impose a more stringent constraint on its yet poorly known coupling strength to the nucleon. This has attracted much attention in connection with the so-called “nucleon-spin crisis” in polarized deep inelastic lepton scattering in that the NNη coupling constant can be related to the quark contribution to the “spin” of the nucleon. Reaction processes where the η meson