Energy dependence of resonance widths

The low-energy behavior of resonance widths can be explained by centrifugal-barrier effects, but this parametrization fails above the resonant energy. A recently proposed model for an inelastic resonance shows that resonance parameters are strongly influenced by an energy-dependent background amplitude. We present calculations for the P₃₃ partial wave in π N scattering which show that the width of the Δ(1236) flattens out above 1450 MeV due to these background effects. We obtain a fit to the background amplitude up to 1800 MeV and find no evidence for a resonance at 1690 MeV.