FEYNMAN RULES AND QUANTUM ELECTRODYNAMICS AT INFINITE MOMENTUM

We have studied the Feynman rules in terms of the new variables s=p0-p3, η=p0+p3, q=(p1,p2) in the φ3 model and in quantum electrodynamics. The connection between the new variables and the dynamics at infinite momentum is established. In the φ3 model, one easily deduces Weinberg's rules at infinite momentum upon integrating over the s variables in the propagators without taking the p3→ limit. The new Feynman rules lead to much simpler calculation of the second-order self-energies and the magnetic moment in quantum electrodynamics. It is still unclear if there is advantage in computing higher-order terms in quantum electrodynamics with the new rules. © 1969 The American Physical Society.