Spectator isobar production in the A(γ,πNN)B reaction

We present an analysis of the spectator mechanism of Δ-isobar production in the pion photoproduction on nuclei with the emission of two nucleons. The reaction mechanism is studied within the framework of the ΔN-correlation model, which considers the isobar and nucleon of the ΔN-system produced in the nucleus at the virtual NN → ΔN transition to be in a dynamic relationship. The two-particle transition operator for nuclei is obtained by the S-matrix approach. We consider the properties of the spectator mechanism of isobar production using the example of the reaction 16O(γ,π-pn)14O. Numerical estimates of the cross-section are obtained in the kinematic region, where it is possible to expect the manifestation of bound isobar-nuclear states.