Three-Particle Channels in Nuclear-Reaction Theory

A new approach to the treatment of three-body channels in nuclear-reaction theory is proposed. The method is based on the $R$-matrix formalism. Instead of introducing three-particle final states as a new class of channels, it is suggested that they be described in terms of incoherent contributions from the various two-body channels having scattering-state residual-nucleus wave functions instead of the customary bound-state ones. The method is (a) illustrated with a simple one-dimensional three-body system, (b) applied to a general three-body system, and finally (c) used to set up a distorted-wave Born-approximation analysis of the general three-body system.