The Influence of Pion-Nucleon Resonance on Elastic Scattering of Charged Pions by Deuterons

Abstract

Almost all experiments^1–3 reported in the literature are at low energy levels, for instance, 60, 85, and 140 MeV; the only experiment available at higher energy is that of Dul’kova et al. ⁴ Theoretical investigation^5–7 based on the impulse approximation accurately fits the experimental data at 60 and 85 MeV, but the agreement between theory and experiment seems to be poor at 140 MeV and the large theoretical cross sections at backward angles cannot be explained away by the on-the-energy-shell multiple scattering effects and the inclusion of s-wave phase shifts and D-state wave functions. As a result of this discrepancy at 140 MeV, Green⁵ has made some skeptical remarks about the validity of the impulse approximation in the energy range of 140 MeV and above. Recently, Pendleton⁸ has made an exhaustive study of the elastic scattering of charged pions at 142 MeV and the effect of the various corrections, using the form factor approximation. His final result does not seem to differ much from the numerical values we obtained earlier⁷ by a simple approach using the Chew-Low amplitude for the scattering of pions by free nucleons.