Kinematical relativistic effects in (vec{e},e'vec{N}) reactions

Kinematical relativistic effects are analyzed within the plane-wave impulse approximation for outgoing nucleon polarized responses in coincidence electron scattering. Following recent approaches for non-relativistic reductions of the electromagnetic current operator, here an exact treatment of the problem for the transferred energy and momentum is presented. Rather than employing existing non-relativistic expressions for the single-nucleon matrix elements, in this work the response functions are expanded directly. Results are compared for different kinematical situations with the fully-relativistic PWIA calculation as well as with previous non-relativistic expansions. Off- and `on-shell' prescriptions are also studied in detail, and a systematic analysis of the various kinematical variables involved in the process is presented.