Worldline representation of multiloop amplitudes in quantum electrodynamics

Abstract

The worldline approach to quantum electrodynamics allows one to construct integral representations combining large numbers of Feynman diagrams. Here I review the state-of-the-art of a long-term effort to make this fact useful for actual multiloop calculations, such as of the scalar and spinor QED vacuum polarization functions and the electron anomalous magnetic moment. After a short historical introduction, and a discussion of the non-standard mathematical challenges involved, I focus on a recent calculation of the two-loop vacuum polarisation in scalar QED and some master integral formulas obtained in this context.

13 pages, 8 figures, talk given by Christian Schubert at Loops and Legs in Quantum Field Theory (LL2026), April 12-17, 2026, Bayreuth, Germany