ABSTRACT
Translations of the scales of the Lu-Fano plots are introduced phenomenologically to bring out the symmetry of two-channel coupling. These shifts in the (v i ) space amount to a phase renormalisation of the Coulomb basis wavefunctions of qdt, which eliminates the diagonal elements of Seaton’s reactance matrix. The off-diagonal element of the resulting matrix measures the effective coupling strength and the new origins of the Lu-Fano plot axes mark the extrema of channel admixture. In the continuous energy range, the parameters (μ̃ i , ξ) provide a compact expression of the cross section for any two-channel (one open and one closed) process, including the whole series of resonances due to the discrete states in the closed channel. A similar generalisation of the Beutler-Fano resonance formula has been previously achieved by Dubau and Seaton.
