Interaction of composite particles

The effective interaction of light nuclear fragments is derived on the basis of resonating group theory. Inclusion of non square integrable distortion and excitation corrections allows to correctly describe the interaction of three fragments in all regions of configuration space. By use of effective interactions the Pauli principle can properly be included in three-body calculations. It is shown that the interaction of nuclear fragments has most of the complicated features which are currently discussed for the interaction of hadrons, especially nucleons. These features arise from the internal structure of the composite particles, together with the Pauli principle, even when the interaction of the constituents is assumed to be simple. A separable approximation scheme for composite particle interaction, which conserves most of the important properties, is discussed and tested in the case of 1=0 α-α scattering. It is seen that relative motion wave functions have rather peculiar properties at distances, where the composite particles interpenetrate. (author)