Green's function of a photon in an external electromagnetic field of a special kind

Photon interaction with a plane monochromatic, circularly polarized wave is investigated in the paper, being propagated along a permanent homogeneous magnetic field. Constraints are found that are imposed on the photon Green's function structure and polarization operator by the common demands of quantum electrodynamics and field symmetry. It is shown that a photon moving in the magnetic field direction can exchange not more than two of its quanta with the external wave.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 3–7, August, 1984.The author is grateful to I. M. Ternov, V. R. Khalilov, A. R. Frenkin, and A. E. Shabad for discussing the results of the research.