Quantum electrodynamics of strong-field Compton scattering and its ponderomotive and drift energies

In earlier classical, semiclassical, and quantum electrodynamical treatments of the Compton scattering in strong fields the strong component of the radiation remained unchanged or forward scattered during interaction with the electron. In our analysis, along with the Compton scattering of a single photon the simultaneous nonforward elastic scattering of the other photons of the intense radiation is also taken into account, resulting in changed kinematical relations that enable the electron to absorb or emit a larger amount of energy up to the ponderomotive energy, in agreement with the experimental results.