Few-body problems in the interacting particle basis

Scattering theory is developed for few-body systems in the interacting particle basis. Problems of three and four particles with pair interaction are reduced to the solutions of one-dimensional Lippmann-Schwinger-type equations with nonlocal, energy dependent, complex potentials. The three- and four-particle channel potentials are determined, which describe particle interaction in the reaction channels. The approximate formulas are found for the three- and four-particle elastic scattering phase shifts which may be useful for the investigation of n-d, n-3He, n-3H scattering at negative and small positive total energies of such systems. (author)