Paper detail

Mixing of pseudoscalar-baryon and vector-baryon in the $J^P=1/2^-$ sector and the $N^*$(1535) and $N^*$(1650) resonances

We study the meson-baryon interaction with $J^P=1/2^-$ 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 $π^- p \to ηn$ scattering is also evaluated and compared with experiment.