We study the infrared behaviour of tree-level QCD amplitudes and we derive infrared-factorization formulae that are valid at any perturbative order. We explicitly compute all the universal infrared factors that control the singularities in the various soft and/or collinear limits at O(as^2).
@article{arxiv.hep-ph/9908523,
title = {Infrared factorization of tree-level QCD amplitudes at the next-to-next-to-leading order and beyond},
author = {S. Catani and M. Grazzini},
journal= {arXiv preprint arXiv:hep-ph/9908523},
year = {2015}
}