Pion absorption on 3He. II. Antisymmetrization and angular decomposition of the Faddeev--based amplitude

In order to develop a procedure for calculation of pion absorption on 3He, we perform the decomposition of the absorption amplitude in three-nucleon partial waves, with full inclusion of antisymmetrization effects among the nucleons. Within this formalism, the matrix elements of the Δ-rescattering term, believed to be the dominant elementary absorption mechanism, are evaluated and embedded in the full (Faddeev-based) nuclear dynamics. This implies the treatment of the 3←3 and 2←3 processes in the final state. Since no attempt is made to include distortions due to the four-body (πNNN) dynamics, the trinucleon bound-state wave function is the only requirement in the initial state.