One-loop Amplitudes: String Methods, Infrared Regularization, and Automation
High Energy Physics - Theory
2026-03-31 v1
Abstract
We calculate field theory loop amplitudes by string methods, applied to half-maximal 4-point one-loop graviton amplitudes. Infrared divergences are regulated similarly to soft-collinear effective field theory (SCET): new mass scales are introduced, here by higher-point kinematics. We use an analytically continued single-valued polylogarithm as generating function. The Feynman integrals for the new tensor structures are infrared finite. We provide code as a step towards automation.
Keywords
Cite
@article{arxiv.2603.26892,
title = {One-loop Amplitudes: String Methods, Infrared Regularization, and Automation},
author = {Marcus Berg and Michael Haack and Yonatan Zimmerman},
journal= {arXiv preprint arXiv:2603.26892},
year = {2026}
}
Comments
57 pages, 10 figures