Are some π−N resonances a manifestation of coupling to the π−Δ(1232) channel?

Abstract

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 P 11, D 13, D 15, and S 31 phase shifts and inelasticities without the need for introducing the P 11(1440), D 13(1520), D 15(1675), and S 31(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.