Coincidence cross sections for coherent pion electroproduction on He and H

We have calculated coincidence cross sections for coherent pion electroproduction on ³He and ³H using Faddeev wave functions obtained with the Reid soft-core potential. The four coincidence structure functions, corresponding to unpolarized and polarized transverse, interference and longitudinal terms differ substantially in their energy dependence. Effects of Fermi motion and off-shell ambiguities are more pronounced for virtual than for real photons. The correct treatment of Fermi motion in the production operator decreases the maximum transverse cross section by up to 50% and lowers the peak energy by up to 50 MeV. Ratios of coherent pion production on ³He and ³H differ significantly for the four structure functions. Finally, the theoretical calculations have been compared with existing experimental data on inclusive pion electroproduction.