The necessity for an improved optical potential in low energy pion-nucleus scattering

Earlier findings that there is a considerable disagreement between theory and experiment in low energy pion-nucleus elastic scattering are confirmed. By explicit calculation, it is shown that this may be largely due to poor πN input. Nevertheless, a residual factor of two difference (in the first peak) could easily be corrected by simple (kinematic and binding) corrections to the first order optical potential.