PI-N-]ETA-N AND ETA-N-]ETA-N PARTIAL-WAVE T-MATRICES IN A COUPLED, 3-CHANNEL MODEL

The πN→ηN and ηN→ηN partial-wave T matrices for the eight lowest partial waves have been obtained in a three-coupled-channel model with unitarity manifestly imposed. The two physical channels are πN and ηN, and the third channel, ππN is an effective, but unphysical two-body channel which represents all remaining processes. The πN elastic phase shifts and the weighted data base of the πN→ηN total and differential cross sections are chosen as the input for the fitting procedure. A model containing a single resonance in each of the three partial waves that dominates the η production at lower energies is compared with previous analyses, based on similar assumptions. A multiresonance coupled-channel model is introduced which significantly improves the agreement with all input data. Our results are compared with a complementary multiresonance coupled-channel analysis that is constrained with elastic and continuum production channels. The inclusion of the fourth P11 resonance in the 1440-2200 MeV region further improves the agreement between the analysis and the data. © 1995 The American Physical Society.