The associated production of a photon and a top-antitop quark pair (ttˉγ) is important for measuring the top-quark charge and probing the top-photon interaction, and it requires improved theoretical predictions. We focus on the calculation of two-loop amplitudes for ttˉγ production at hadron colliders. The infrared singularities with full top-quark mass dependence are derived from universal anomalous dimensions combined with one-loop massive amplitudes expanded to higher orders in the dimensional regulator ϵ. The finite remainders are approximated in the high-energy boosted limit using the mass-factorization formula. To validate our approach, we compare approximate one-loop amplitudes up to O(ϵ2), as well as the two-loop infrared poles, against our exact results. The results in this paper serve as an important step toward next-to-next-to-leading order predictions for ttˉγ production.
@article{arxiv.2510.01774,
title = {Two-loop QCD amplitudes for $t\bar{t}\gamma$ production at hadron colliders},
author = {Guoxing Wang and Li Lin Yang},
journal= {arXiv preprint arXiv:2510.01774},
year = {2025}
}