We study quantum electrodynamics (QED) in the light-front dynamical form by using null-plane causal perturbation theory. We establish the equivalence with instant dynamics for the scattering processes, whose normalization allows one to construct the instantaneous terms of the usual null-plane QED Lagrangian density. Then we study vacuum polarization and normalize it by studying its insertions into Møller’s scattering process, obtaining the complete photon propagator, which turns out to be equivalent to the one of instant dynamics only when gauge invariance is taken into account.

• Received 7 March 2022
• Accepted 15 July 2022

DOI:https://doi.org/10.1103/PhysRevD.106.016014

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Published by the American Physical Society