The pion-nucleus optical potential in the isobar-doorway model is extended to isospin nonzero nuclei. Many-body effects in isobar propagation are parametrized in terms of an energy shift and width and an isobar nonlocality. Isospin dependence of these parameters is found to play an important role in determining pion charge exchange cross sections.

NUCLEAR REACTIONS Pion charge exchange, isobar-doorway optical potential model, isospin-dependent modification of isobar propagator.

• Received 5 October 1979

DOI:https://doi.org/10.1103/PhysRevC.21.1111