Pion photoproduction on nucleus with two-nucleon emission

A model for the pion photoproduction on nuclei in the image reaction is presented. This is an extension of our recent model for the image reaction. In this approach we have moved beyond the standard shell-model considering ΔN correlations in the nuclear wave functions, which are caused by the virtual transitions image in the ground state of the nucleus. The main ingredients of the model are the two- and three-particle density matrices and the transition operators image and image. The direct and exchange reaction mechanisms, which follow from the structure of the density matrices, are examined. The model is used to investigate the 12Cimage and 12Cimage reactions in the kinematic region of the large momentum transfers to the residual nuclear system, where the pion production occurs with the emission of two nucleons. Signatures of the ΔN correlations in the exclusive cross-sections of the 12Cimage10Be reaction are considered.