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Article
Report number	arXiv:1912.06425 ; CERN-TH-2019-221 ; CP3-19-57
Title	Tree-level splitting amplitudes for a quark into four collinear partons
Author(s)	Del Duca, Vittorio (Zurich, ETH) ; Duhr, Claude (CERN) ; Haindl, Rayan (Zurich, ETH) ; Lazopoulos, Achilleas (Zurich, ETH) ; Michel, Martin (Louvain U., CP3)
Publication	2020-02-28
Imprint	2019-12-13
Number of pages	46
Note	4 figures
In:	JHEP 2002 (2020) 189
DOI	10.1007/JHEP02(2020)189
Subject category	hep-ph ; Particle Physics - Phenomenology
Abstract	We compute in conventional dimensional regularisation the tree-level splitting amplitudes for a quark parent in the limit where four partons become collinear to each other. This is part of the universal infrared behaviour of the QCD scattering amplitudes at next-to-next-to-next-to-leading order (${\rm N^3LO}$) in the strong coupling constant. Further, we consider the iterated limit when $m'$ massless partons become collinear to each other within a bigger set of $m$ collinear partons, as well as the limits when one gluon or a $q\bar{q}$ pair or two gluons become soft within a set of $m$ collinear partons.
Copyright/License	preprint: (License: arXiv nonexclusive-distrib 1.0) publication: © 2020-2025 The Authors (License: CC-BY-4.0)

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