Non-resonance annihilation of electron-positron pair in the field of light wave

The non-resonance two photon annihilation of e^-e⁺ pair in the presence of circularly polarized electromagnetic wave is considered. The expression for partial annihilation cross section averaged over the polarizations of the initial electrons (positrons) and summed over the quanta is determined for moderately strong field. 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 the 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. It is demonstrated that non-resonant cross section may differ some times from the cross section of the corresponding process in the absence of the external field.