Eigenchannel Theory of Nuclear Reactions

A method is proposed by which the eigenstates and the eigenvalues of the $S$ matrix, i.e., the eigenchannels, can be directly computed from the nuclear problem, for example, from the shell model. The calculation of all cross sections, viz., partial and total cross sections, is then exceedingly simple. The characteristics of the eigenchannels are described and the relation with other reaction theories is briefly discussed.