Some Remarks on the Vertex Function

Abstract

It is noted that the integral representations for matrix elements derived in three papers, (1) Dyson, (2) Deser, Gilbert, and Sudarshan, and (3) Faĭnberg, do not give the most general functions satisfying the conditions stated. It is shown that in (1) and (2) the convergence of certain integrals was not treated rigorously, while in (3) there was a misunderstanding of the Jost-Lehmann-Dyson representation.