Asymmetries and dark angular windows in relativistic free-free transitionsin a powerful laser field

We consider potential scattering of electrons in a powerful laser held. The laser-dressed electron is described by the solution of the Klein-Gordon eq uation in a powerful plane-wave radiation field. The scattering process is treated in the first Born approximation. It is shown that the differential cross sections of induced and inverse bremsstrahlung are asymmetric with re spect to the direction of propagation of the radiation field. This asymmetr y has its origin in the laser-induced dl-ift motion of the electrons and sh ould, by present day experimental standards, become an observable effect. N umerical calculations also show the existence of broad dark angular windows , i.e., scattering angles for which the nonlinear cross sections are margin al. The positions of such windows depend on the laser field intensity as we ll as an the nonlinearity of the laser-induced scattering process. [S1050-2 947(99)02603-7].