Interference suppression in the two-photon annihilation of an electron-positron pair in the light wave field

Nonresonant two-photon annihilation of an electron-positron pair in the field of a moderately strong circularly polarized wave is investigated theoretically. The partial cross-section can be summed over all processes of emission and absorption of photons. It is shown that all essentially quantum contributions caused by the Bunkin-Fedorov quantum parameter are compensated for both Feynman diagrams and are not compensated for the quantum process of interference of these diagrams. The external field has an effect on the interference term through the Bunkin-Fedorov quantum parameter. As a result the nonresonant differential cross-section can differ from that in the absence of the external field.