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arXiv · 2103.12850

One-loop multicollinear limits from 2-point amplitudes on self-dual backgrounds

Tim Adamo·Anton Ilderton·Alexander J. MacLeod
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Abstract

For scattering amplitudes in strong background fields, it is -- at least in principle -- possible to perturbatively expand the background to obtain higher-point vacuum amplitudes. In the case of self-dual plane wave backgrounds we consider this expansion for two-point, one-loop amplitudes in pure Yang-Mills, QED and QCD. This enables us to obtain multicollinear limits of 1-loop vacuum amplitudes; the resulting helicity configurations are surprisingly restricted, with only the all-plus helicity amplitude surviving. These results are shown to be consistent with well-known vacuum amplitudes. We also show that for both abelian and non-abelian supersymmetric gauge theories, there is no helicity flip (and hence no vacuum birefringence) on any plane wave background, generalising a result previously known in the Euler-Heisenberg limit of super-QED.

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Tim Adamo, Anton Ilderton, Alexander J. MacLeod. 2021-03-23. One-loop multicollinear limits from 2-point amplitudes on self-dual backgrounds. https://doi.org/10.1007/jhep12(2021)207

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