Feinberg-Pais Equation for the Trace of Ladder Diagrams
John Charlton Polkinghorne, John C. Taylor · Physical Review · 1964
The equations of Feinberg and Pais for the trace of the sum of ladder diagrams in lepton scattering are examined by summing Feynman diagrams, and also in configuration space. Both methods establish the truth of a conjecture made by Feinberg and Pais: that the equation is equivalent to one which may be iterated without generating divergent integrals.