Nucleon resonances in πN scattering up to energies \sqrt(s) < 2.0 GeV

Abstract

A meson-exchange model for pion-nucleon scattering was previously constructed using a three-dimensional reduction scheme of the Bethe-Salpeter equation for a model Lagrangian involving π, η, N, Δ, ρ, and σfields. We thereby extend our previous work by including the ηN channel and all the πN resonances with masses ~ 2 GeV, up to the F waves. The effects of the ππN channels are taken into account by introducing an effective width in the resonance propagators. The extended model gives an excellent fit to both πN phase shifts and inelasticity parameters in all channels up to the F waves and for energies below 2 GeV. We present a new scheme to extract the properties of overlapping resonances. The predicted values for the resonance masses and widths as well as resonance pole positions and residues are compared to the listing of the Particle Data Group.

24 pages, 6 figures, 4 tables; corrections were made in Eqs. 33, 38 and in caption of Fig.3