Infrared factorization of tree-level QCD amplitudes at the next-to-next-to-leading order and beyond Original Research Article

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(αS2).