Classical and Quantum Radiation Reaction

Abstract: This thesis reports on work undertaken in comparing the effects
of the phenomenon of radiation reaction in classical and quantum theories of
electrodynamics. Specifically, it is concerned with the prediction of the change
in position of a particle due to the inclusion of the self-force in the theory. We
calculate this position shift for the classical theory, treating radiation reaction
as a perturbation in line with the reduction of order procedure. We calculate
the contributions to the position shift in the Ii -t 0 limit of quantum field
theory to order e2 in the coupling, the order of the classical self-force. Thes~
calculations contain the emission and forward scattering one loop processes of
quantum electrodynamics. The quantum calculations are completed for the
case of a particle represented by a scalar field wave packet and then for a particle
represented by the Dirac spinor field. We additionally give an alternative
derivation of the scalar results using the interpretation of radiation reaction
via a Green's function decomposition, in order to explain and contrast the
results achieved.