Polarization of recoil photon in nonlinear Compton process

The polarization of recoil photon ( γ ′ ) in the nonlinear Compton process e + L → → γ → ′ + e ′ in the interaction of a relativistic electron with a linearly polarized laser beam ( L → ) is studied within the Furry picture in the lowest order, tree-level S matrix element. In particular, we consider the asymmetry of differential cross sections A for two independent axes describing the Compton process equal to the intrinsic spin variable ξ 3 f that determines the polarization properties of γ ′ . The sign and absolute value of the asymmetry determine the direction and degree of γ ′ polarization. We have analyzed the process in a wide range of laser intensity that covers existing and future experiments. Our results provide additional knowledge for studying nonlinear multi-photon effects in quantum electrodynamics and can be used in planning experiments at envisaged laser facilities. Graphical abstract