Distortion operator approach and [N, 1] Padé sequence in nonrelativistic scattering theory

A brief account of the scattering theory using the so called distortion operator is given. The Neumann series for a matrix element of the distortion operator is proved to imply the [N, 1] Padé sequence for the transition matrix element. As a consequence a region of convergence of the [N, 1] Padé sequence is found.