Mixing of Pseudoscalar-Baryon and Vector-Baryon in the JP = 1/2− Sector and the N*(1535) and N*(1650) Resonances

We study the meson-baryon interaction with = 1/2^− using the hidden-gauge Lagrangians and mixing pseudoscalar meson-baryon with the vector meson-baryon states in a coupled channels scheme with πN, ηN, KΛ, KΣ, ρN, and πΔ (d-wave). We fit the subtraction constants of each channel to the S_11 partial wave amplitude of the πN scattering data extracted from experimental data. We find two poles that we associate to the N^*(1535) and the N^*(1650) resonances and show that the subtraction constants are all negative and of natural size. We calculate the branching ratios for the different channels of each resonance and we find a good agreement with the experimental data. The cross section for the π^−p → ηn scattering is also evaluated and compared with experiment.