Quantum Electrodynamics in the Infinite-Momentum Frame

Abstract

We examine the formal foundations of quantum electrodynamics in the infinite-momentum frame. We interpret the infinite-momentum limit as the change of variables $\ensuremath{\tau}={2}^{\ensuremath{-}\frac{1}{1}}(t+z)$, $\mathcal{Z}={2}^{\ensuremath{-}\frac{1}{1}}(t\ensuremath{-}z)$, thus avoiding limiting procedures. Starting from the Feynman rules, we derive a $\ensuremath{\tau}$-ordered perturbation expansion for the $S$ matrix. We then show how this expansion arises from a canonical formulation of the field theory in the infinite-momentum frame. We feel that this approach should lead to convenient approximation schemes for electrodynamics at high energy.