PION-NUCLEUS MANY-BODY PROBLEM

Low energy pion-nucleus elastic scattering is discussed within the framework of many-body theory. In these considerations exchange of virtual ρ ad π mesons, as well as the π meson, are found to play an important role, producing effects like the Ericson-Ericson Lorentz-Lorenz effect. By inclusion of interactions in channels other than the pionic one, the pion-nucleus problem is brought into the context of other nuclear many-body problems, and various relations to the nucleon problem made use of . Some of the necessary parameters here are drawn from pionic atom work. With these and our deduced interactions the theoretically predicted cross-sections are found to be in good agreement with the experimental work. © 1979.