Abstract
A general unitary phenomenological description of strongly interacting three-particle systems is developed in terms of two-particle phase shifts and binding energies, two-particle wave functions inside the range of forces, and the three-body wave function in the region where all three force ranges overlap. The two-particle external and internal parameters are unambiguously separated from each other and the same parameters can be determined from many different experiments, while the three-body parameters refer to a specific system at a specific energy.