
%0 Journal Article
%A Nicholson, AF 
%T Elimination of Primitive Divergents from Field Theory by Means of Complex Coupling Constants
%J Australian Journal of Physics
%D 1973/12/01
%V 26
%N 6
%P 703-724
%K 
%R https://doi.org/10.1071/PH730703
%U https://www.publish.csiro.au/paper/PH730703 
%X LSZ. iteration theory is extended to accommodate quantum fields coupled by complex constants, while retaining a positive metric and a Hermitian Hamiltonian. Interpolating and particle (~in, out) fields are linked by an operator U(t) which is nonunitary, so that Haag's theorem may be avoided. It is shown that U(t) may be rendered sufficiently well-behaved as t -+ ± 00 to allow development of the iteration series for the T function. For certain combinations of fields the coupling constants and masses can then be chosen so as to eliminate the primitive divergents from the iteration series for any S-matrix element. The theory is illustrated by two models: four spinor plus two scalar fields, and the electromagnetic plus several spinor fields. In the second model not every spinor field corresponds to a stable physical particle, and the LSZ formalism is extended to allow for this. 
