A discussion of several kinematical schemes used in the study of pion-nucleus scattering is presented. It is shown that various kinematical ambiguities of the noncovariant theories are resolved in a covariant analysis. In particular, the use of an off-mass-shell description for the projectile and the target particles provides a degree of freedom in the kinematical description which avoids various problems present in the noncovariant analyses. We present a comparison of the angle transformations, matrix elements, and differential cross sections obtained from the different kinematical specifications. In these comparisons we have attempted to maintain a clear separation of the dynamical and kinematical assumptions, using the same pion-nucleon interaction in all the cases considered. It is found that the large angle scattering is most sensitive to the details of the kinematical description.

NUCLEAR REACTIONS Scattering theory, pion optical potential, comparison of kinematic transformations.

• Received 23 June 1975

DOI:https://doi.org/10.1103/PhysRevC.12.1983