Microscopic theory of the intermediate structure of gigantic resonances in nuclear reactions

The microscopic theory of the coupling between a particle and a hole with more complex states is developed. Particular attention is given to considering coupling with two-particle - two-hole states. It is shown that particle-hole states plus the low-lying collective state play an important role. As regards the extent to which interaction between the particles is taken into account a comparison is made with the theory of finite Fermi systems. The results obtained using the microscopic theory are compared with the corresponding results obtained using the phenomenological theory. A correspondence is established between the parameters of the model considered. When an appropriate choice of the parameters is made and the formfactors are matched, the matrix elements of the interaction between the nucleon and the core calculated by the two models are practically identical.