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The AN -+ gN and gN~gN 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 AN and gN, and the third channel, vr7rN, is an effective, but unphysical two-body channel which represents all remaining processes. The 7tN elastic phase shifts and the weighted data base of the mN~gN 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 g 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 Pqq resonance in the 1440 -2200 MeV region further improves the agreement between the analysis and the data. PACS number(s): 25.40.Ve, 13.75.Gx, 14.40. Aq, 24. 10.Eq

The total cross section for the near threshold η production in proton-proton collisions has been investigated with the assumption that the production mechanism is due to the emission of a meson x(π, η, σ) from one of the nucleons followed by a xN → ηN transition on the second one. The xN → ηN amplitudes are generated from the unitary multi-channel multi-resonance model which has recently been constructed in analyzing the πN scattering and πN → ηN reaction. The initial and final pp distortions are calculated from a coupled-channel πN N model which describes the N N scattering data up to about 2 GeV. With the x − N N vertex functions taken from the Bonn potential, the predicted total cross sections of threshold pp → ηpp reaction are in good agreement with the data. In contrast to previous works, we find that the η-exchange plays an important role. The effect of the two-pion exchange, simulated by σ-exchange, is found to be significant but not as dominant as the vector meson-exchange introduced in previous works.The η production in proton-proton collisions has attracted a lot of interest in the past decade. A theoretical understanding of this two-nucleon process near the production threshold is needed for exploring the N * (S 11 (1535)) dy-

A three-channel, multi-resonance, unitary model developed in 1995 is used to determine the πN → ηN and ηN → ηN amplitudes by re-analyzing the available data on πN elastic scattering and the weighted data for the πN → ηN total and differential cross sections. The input πN elastic scattering amplitude in the S11 channel has been improved, following suggestions of G. Höhler. Our new result of ηN scattering length, aηN = (0.717±0.030)+i · (0.263±0.025) fm, suggests that the ηd system is unbound or loosely bound.

The Zagreb analysis partial-wave T matrices included in the Review of Particle Physics [by the Particle Data Group (PDG)] contain Breit-Wigner parameters only. As the advantages of pole over Breit-Wigner parameters in quantifying scattering matrix resonant states are becoming indisputable, we supplement the original solution with the pole parameters. Because of an already reported numeric error in the S 11 analytic continuation [Batinić et al., Phys. Rev. C 57, 1004(E) (1997); arXiv:nucl-th/9703023], we declare the old BATINIC 95 solution, presently included by the PDG, invalid. Instead, we offer two new solutions: (A) corrected BATINIC 95 and (B) a new solution with an improved S 11 π N elastic input. We endorse solution (B).