engleski

π N→ η N and η N→ η N partial-wave T matrices in a coupled, three-channel model

The π N→ η N and η N→ η N 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 π N and η N, and the third channel, π π N is an effective, but unphysical two-body channel which represents all remaining processes. The π N elastic phase shifts and the weighted data base of the π N→ η N 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.

The π N elastic phase shifts; differential cross sections

nije evidentirano