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

We present an analysis of the spectator mechanism of [Formula: see text]-isobar production in the pion photoproduction on nuclei with the emission of two nucleons. The reaction mechanism is studied within the framework of the [Formula: see text]-correlation model, which considers the isobar and nucleon of the [Formula: see text]-system produced in the nucleus at the virtual [Formula: see text] 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 [Formula: see text]O[Formula: see text]O. 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.