Universal structure of radiative QED amplitudes at one loop

Engel, T.; Signer, A.; Ulrich, Y.

Abstract

We present two novel results about the universal structure of radiative QED amplitudes in the soft and in the collinear limit. On the one hand, we extend the well-known Low-Burnett-Kroll theorem to the one-loop level and give the explicit relation between the radiative and non-radiative amplitude at subleading power in the soft limit. On the other hand, we consider a factorisation formula at leading power in the limit where the emitted photon becomes collinear to a light fermion and provide the corresponding one-loop splitting function. In addition to being interesting in their own right these findings are particularly relevant in the context of fully-differential higher-order QED calculations. One of the main challenges in this regard is the numerical stability of radiative contributions in the soft and collinear regions. The results presented here allow for a stabilisation of real­virtual amplitudes in these delicate phase-space regions by switching to the corresponding approximation without the need of explicit computations.

Citation

Engel, T., Signer, A., & Ulrich, Y. (2022). Universal structure of radiative QED amplitudes at one loop. Journal of High Energy Physics, 2022(4), Article 97. https://doi.org/10.1007/jhep04%282022%29097

• Journal Article Type: Article
• Acceptance Date: Mar 22, 2022
• Online Publication Date: Apr 15, 2022
• Publication Date: 2022
• Deposit Date: May 4, 2022
• Publicly Available Date: May 5, 2022
• Journal: Journal of High Energy Physics
• Print ISSN: 1126-6708
• Electronic ISSN: 1029-8479
• Publisher: Scuola Internazionale Superiore di Studi Avanzati (SISSA)
• Peer Reviewed: Peer Reviewed
• Volume: 2022
• Issue: 4
• Article Number: 97
• DOI: https://doi.org/10.1007/jhep04%282022%29097
• Public URL: https://durham-repository.worktribe.com/output/1207977