Zur Störung der Kohärenz zweiter Ordnung durch Wechselwirkung

A definition of the disturbance of the second order coherence of a photon field, scattered by an electron, is formulated within the framework of quantum electrodynamical coherence theory. As a special case forward scattering is considered, thus yielding a simple relation with the matrix element for one-photon-scattering. The scattering on a free polarized electron is treated as an example.