Pion Induced Double Charge Exchange Reaction at Pure Nucleonic Level

The two pure nucleonic mechanisms (the conventional sequential mechanism and the two-nucleon pion absorption-emission mechanism[1]) are studied within a unified framework of Distorted Wave Impulse Approximation (DWIA). The distorted pion waves are obtained by solving the Klein-Gordon equation with the first-order optical potential. The difference between this approach and the eikonal approximation is showed. For the two-nucleon pion absorption-emission mechanism the effective Landau-Migadal interaction of Pines, et al.[2] is used for the two bound nucleons, the result is compared with that by using the Paris force. By combining these two mechanism the 0° excitation functions for the DCX reactions to the isobaric analog states on the 14C, 18O, 26Mg and 42Ca are calculated and compared with the experimental data.