Method of evolution in the coupling constant (inelastic processes)

The method of evolution in the coupling constant, which was used earlier to describe only elastic processes, is used as the basis for a new way of dealing with inelastic multichannel processes of a general type. The coupling-constant differential equations for the elastic-channel amplitudes are supplemented by simple algebraic equations for inelastic transitions, so that altogether a complete and unique solution is obtained which incorporates unitarity in each stage of the successive approximations. The use of the method is illustrated for the case of particle scattering by a bound complex which has several excitation levels