“…This partitioning, along with an orthogonality assumption of channels at the channel boundary, is what we could call the R-matrix scattering model, described by Kapur and Peierls in their seminal article [12], unified by Bloch in [13], and reviewed by Lane and Thomas in [5]. It is possible to study the general energy and wavenumber dependence of the scattering matrix emerging from this model, and such expansions were thoroughly studied by Humblet and Rosenfeld in [2, [14][15][16][17][18][19][20][21]. Alternatively, this wave-number dependence of the different possible outgoing particle-waves stemming from the R-matrix model can be parametrized, for calculablility reasons, in several ways.…”