On the Convergence of the Perturbation Method in the Quantum Field Theory
R. Utiyama · Progress of Theoretical Physics · 1953
The convergence of the Green-functions of one-nucleon and one-meson problems is investigated. In order to get the finite expressions for these Green-functions, we define the vertex function Γ by (1 cdot 9). By virtue of this definition the number of graphs of the proper vertex-type of the n-th order in g increases so slowly that the majorant series of the Green-function can be made to converge.