Kinematical relativistic effects in ((e)over-right-arrow, e′ (N)over-right-arrow) 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 semi-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 semi-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 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. (C) 2002 Elsevier Science B.V. All rights reserved.