Lebed O. Nonlinear effects in quantum electrodynamics processes in a strong pulsed laser field

This thesis includes the theoretical study of physical processes in a pulsed laser field by the quantum-electrodynamics methods. The kinematic features of the processes of scattering of an electron by a nucleus, an electron on an electron, bremsstrahlung of an electron and the production of an electron-positron pair by a photon on a nucleus in the presence of an external pulsed field of one and two laser waves are studied. A theory of these processes is developed. Explicit expressions are obtained for the transition amplitudes and differential cross sections. The energy and angular distributions for the particles in the final state are investigated. A comparative analysis is carried out for models of a monochromatic and pulsed laser wave. A systematic analysis of physical processes in a pulsed field is carried out under resonant conditions, in the case of two waves with correlation of radiation and absorption of photons of the laser field, with scattering of fast particles at small angles and small transferred momenta, in the case when the energy of the field, which is absorbed or emitted by a particle, is one of the order of magnitude with the initial kinetic energy of the particles. A method was developed regard to elimination of the nonphysical resonance divergence in the amplitude and cross-section of the processes in a pulsed laser field. It is shown that under special kinematic conditions, nonlinear effects can lead to a significant increase of the cross sections of quantum electrodynamics processes in an external laser field.