Using separable potentials for the processes πN → πN, πN → πΔ, and πΔ → πΔ, we investigate the possibility that some of the low lying resonances seen in π-N elastic scattering may be due to the opening of the threshold for π-Δ production. We find excellent fits to the P11, D13, D15, and S31 phase shifts and inelasticities without the need for introducing the P11(1440), D13(1520), D15(1675), and S31(1620) resonances explicitly. While not claiming that true particle resonances do not exist, our results indicate that coupling to the π - Δ channel should not be ignored.
Bibliographical noteFunding Information:
This work is supporteidn part by the National ScienceF oundation.