Tree-level splitting amplitudes for a quark into four collinear partons
Vittorio Del Duca, Claude Duhr, Rayan Haindl, Achilleas Lazopoulos, Martin C. Michel
Abstract
A bstract 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 (N 3 LO) 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 $$ \overline{q} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mover> <mml:mi>q</mml:mi> <mml:mo>¯</mml:mo> </mml:mover> </mml:math> pair or two gluons become soft within a set of m collinear partons.