The intermediate-state interaction and structure of amplitudes of complicated processes in medium (decays, reactions and the $n\bar{ n}$ transitions) are studied. It is proposed to use the branching ratio of channels of free-space hadron-nucleon interaction as a test in the construction and verification of the models. The corresponding formulas for the processes in the medium are obtained. The connection between particle self-energy and amplitudes of subprocesses are analyzed as well.
Categories: nucl-th hep-ph