Effective interactions in many-body scattering obtained by a systematic subtraction technique

Summary  Starting from exact integral equations for many-body scattering, we use a subtraction technique to separate the two-cluster, …,N-cluster parts of the integral kernels. We obtain one-vector variable integral equations (basic equations) having a coupled-reaction-channel-like structure together with a sequence of two-vector, …, (N — 1)-vector variable integral equations (auxiliary equations) with increasingly simple kernels, which can be successively solved starting from the last one. The solutions of the sequence of the auxiliary equations yield the effective interactions to be inserted into the basic equations. This formulation is highly flexible, so that different degrees of approximation can be readily introduced.