η meson production in both proton-proton and proton-neutron collisions is investigated within a relativistic meson exchange model of hadronic interactions. It is found that the available cross section data can be described equally well by either the vector or pseudoscalar meson exchange mechanism for exciting the S 11 (1535) resonance. It is shown that the analyzing power data can potentially be very useful in distinguishing these two scenarios for the excitaion of the S 11 (1535) resonance.

The reactions γp → π 0 p and γp → π + n are analyzed in a semi-phenomenological approach up to E ∼ 2.3 GeV. Fits to differential cross section and single and double polarization observables are performed. A good overall reproduction of the available photoproduction data is achieved. The Jülich2012 dynamical coupled-channel model -which describes elastic πN scattering and the world data base of the reactions πN → ηN , KΛ, and KΣ at the same time -is employed as the hadronic interaction in the final state. The framework guarantees analyticity and, thus, allows for a reliable extraction of resonance parameters in terms of poles and residues. In particular, the photocouplings at the pole can be extracted and are presented.

Elastic πN scattering and the world data of the family of reactions π − p → ηn, K 0 Λ, K 0 Σ 0 , K + Σ − , and π + p → K + Σ + are described simultaneously in an analytic, unitary, coupled-channel approach. SU(3) flavor symmetry is used to relate both the t-and the u-channel exchanges that drive the meson-baryon interaction in the different channels. Angular distributions, polarizations, and spin-rotation parameters are compared with available experimental data. Partial-wave amplitudes are determined and the resonance content is extracted from the analytic continuation, including resonance positions and branching ratios, and possible sources of uncertainties are discussed. The results provide the final-state interactions for the ongoing analysis of photo-and electroproduction data.