Towards a relativistic manybody procedure
Abstract
A review is given of the nonrelativistic manybody perturbation theory (MBPT), and an analysis is made about the possibilities of extending this scheme to the relativistic regime in a rigorous and systematic manner. The nonrelativistic MBPT is here based upon the iterative solution of coupled one and twoparticle equations, which yields the polarization (oneparticle) and paircorrelation (twoparticle) effects to all orders of perturbation theory. Illustrative numerical results are given. The analysis of the relativistic problem is based upon the covariant treatment of the electronelectron interaction (Feynman gauge) with the exchange of one and two virtual photons. The first approximation leads to the socalled novirtualpair approximation, where the effect of virtual electronpositron pairs as well as Lambshift corrections are neglected. Here, a numerical procedure quite similar to that employed in the nonrelativistic case has been developed by the Chalmers group, and some results are given. The effects beyond the novirtualpair approximation cannot be taken into account in a complete and rigorous way by means of a single potential. For the paircorrelation problem at least two potentials are needed, and in addition there are threebody potentials etc. Furthermore, these potentials are energy dependent, so an exact calculation seems to require explicit construction of the intermediate states.
 Publication:

Nuclear Instruments and Methods in Physics Research B
 Pub Date:
 April 1988
 DOI:
 10.1016/0168583X(88)904016
 Bibcode:
 1988NIMPB..31..102L