Does it make sense to talk about NΔ phase shifts?

Abstract

The question of whether one can consistently define and extract nucleon-delta scattering parameters, phase shifts, and inelasticities from the partial-wave NN→NΔ amplitudes is discussed. We have studied the unitarity relation and identified the conditions under which the extraction of such quantities is meaningful. Then these conditions were tested in several coupled-channel models of the NN-NΔ system.