Multichannel generalization of eigenphase-preserving supersymmetric transformations

We generalize eigenphase-preserving (EPP) supersymmetric (SUSY) transformations to an N  >  2 channel Schrödinger equation with equal thresholds. It is established that EPP SUSY transformations exist only in the case of an even number of channels, N = 2M. A single EPP SUSY transformation provides an M(M − 1) + 2 parametric deformation of the matrix Hamiltonian without affecting eigenphase shifts of the scattering matrix. (paper)