Double poles of the S-matrix in laser-assisted electron-atom scattering

We discuss two double-resonance scenarios within the context of laser-assisted electron-atom scattering in which double poles of the S -matrix occur. We demonstrate the effect of the double poles on the resonant contribution to the cross-section as well as on the time delay matrix and we point out that double poles could be observed experimentally at quite modest intensities and at frequencies corresponding to existing lasers.