KROLL-WATSON-TYPE THEOREM FOR POTENTIAL SCATTERING IN A BICHROMATIC LASER FIELD

We show that for potential scattering of electrons in a bichromatic la ser field a Kroll-Watson type of theorem can be derived in which the s cattering T-matrix element is composed of a renormalized on-shell matr ix element for scattering without a field times a generalized Bessel f unction factor. The radiation field has two components of frequency om ega1 and somega1 (s = 2, 3, ...) and both components are out of phase by an angle phi. Our paper is a generalization of earlier investigatio ns which were performed in the first-order Born approximation.