Three Body Model for P Wave PION-OXYGEN-16 Scattering.

A three body model has been used to derive the first order optical potential for elastic scattering of pions from ('16)O using multiple scattering theory. The interaction between the pion and a nucleon is described by a separable potential in the relative p state of the pion and the nucleon in the J = I = 3/2 channel. In this model the binding of the nucleons to the nucleus is provided by a shell model potential which is of the Woods-Saxon type. The effect of binding is treated nonperturbatively by solving, in coordinate space, a set of coupled differential equations which describe the elastic and excited channel wavefunctions. Coordinates from the center of binding to the pion and the nucleon are used for the elastic channel, while the pion-nucleon center of mass coordinates are used for the excited channel wavefunction. It is found that the nuclear structure effects implied by the finite binding potential alter the results significantly from those in impulse approximation.