The π+d ↔ pp and π+ t ↔ pd reactions with the rescattering model

The rescattering model is used to study pion absorption/production processes on A=2 and A=3 nuclei. In the A=2 case, the calculation includes the effects of pion-nucleon rescattering in S- and P-waves. In the latter case, the effects due to the isobar degrees of freedom in the intermediate states are included. These dominate the process of pion absorption at Tπ = 100 - 150 MeV. Isobar-excitation effects are then considered in the A=3 case, and the outputs of first calculations of this sort are shown and discussed. The effect of nucleon-nucleon rescattering (FSI) are considered in both situations involving two and three nucleons. 27 refs., 1 tab., 8 figs