Pion-deuteron scattering and the optical potential

We have calculated the pion-deuteron elastic, total, and differential cross sections for energies between 100 and 300 MeV, using two forms of the optical potential similar to those used in the theory of pion-nucleus scattering. We have studied the accuracy of the optical potential descriptions, by comparing these cross sections with the exact ones that are obtained by solving the relativistic Faddeev equations. We found that in all cases the optical potential overestimates the multiple scattering corrections. We interpret this result as meaning that the optical potential series may not converge for pion-nucleus scattering. NUCLEAR REACTIONS -d optical potentials; E=100-300 MeV; calculated tot, el, and dd.