Parity nonconserving two-pion exchange in elastic proton-proton scattering

Parity nonconserving two-pion exchange in elastic pp scattering is investigated in the presence of phenomenological strong distortions in various models. Parity violation is included in the nucleon-pion vertex considering NN and N Delta(1232) intermediate states in box and crossed box diagrams. Using the derived parity nonconserving two-pion exchange potential we calculate the longitudinal analyzing power A_L in elastic $pp$ scattering. The predicted effect is of the same order as vector meson exchanges.