[NT/RBRC seminar] High-order computations in the worldline space: the QED cusp anomalous dimension

by Dr Xabier Feal (Santiago de Compostela University)

Friday 7 Jul 2023, 11:00 → 13:00 US/Eastern

Large seminar room (https://bnl.zoomgov.com/j/1614715193?pwd=WkwxODVWdzZzb29zQnZRVGp3VTBDQT09)

In 2206.04188 and 2211.15712 we developed and discussed a complete reformulation of QED as a many-body theory of 0+1-dimensional worldline fermions. In the worldline formulations of QFTs, one integrates over the trajectories that point-like particles follow in space-time rather than over fields, with their internal degrees of freedom (spin or color) exactly described with anti-commuting variables along their paths. In these recent works, we showed how these formulations in terms of particle variables become natural to discuss non-perturbative IR effects of the gauge interactions. In particular, we showed there how soft theorems follow in this framework, and we delivered an all-order proof of the IR safety of the Faddeev-Kulish S-matrix, a manifestly IR finite formulation of QED. In this talk I will show how this powerful formulation also offers clear calculational advantages for high-order perturbative calculations over the conventional methods of field perturbation theory, i.e. Feynman diagrams. I will demonstrate this point by discussing our ongoing work on the high-order computation of QED cusp anomalous dimensions.