Abstract
A reaction mechanism is developed to describe the coherent production of pions in the A(3He, pi +)B processes leading to discrete states of the final nucleus B. The model uses as input experimental data on the 3He(p, pi +)4He reaction and a cluster decomposition of the state B. It is studied in detail for 3He and 4He targets and many of the qualitative features of the experimental energy and angular dependence are then reproduced.