Photon-induced post-collisional Auger decay. A two-potential complex coordinate formalism

Photon-induced, post-collisional Auger decay processes are studied near to excitation threshold situation. The Gell-Mann-Goldberger two-potential formalism is applied for deriving the transition amplitudes which are shown to be dominated by the second-order terms. The combination of the two-potential formalism with the spectral analysis following from the complex coordinate method has been shown to be applicable in the treatment of the final-state interactions. Expressions for the scattering amplitude are derived without sudden impulse arguments. As the result of the complex coordinate treatment, the scattering amplitude distinctly separates into direct, background and resonant parts.