CERN Accelerating science

Article
Report number	arXiv:2207.07441
Title	High-energy limit of 2->2 scattering amplitudes at NNLL
Author(s)	Milloy, Calum (Turin U. ; INFN, Turin) ; Falcioni, Giulio (Edinburgh U. ; U. Edinburgh, Higgs Ctr. Theor. Phys.) ; Gardi, Einan (Edinburgh U. ; U. Edinburgh, Higgs Ctr. Theor. Phys.) ; Maher, Niamh (Edinburgh U. ; U. Edinburgh, Higgs Ctr. Theor. Phys.) ; Vernazza, Leonardo (Turin U. ; INFN, Turin ; CERN)
Publication	2022-10-20
Imprint	2022-07-15
Number of pages	11
In:	PoS LL2022 (2022) 044
In:	16th DESY Workshop on Elementary Particle Physics: Loops and Legs in Quantum Field Theory 2022, Ettal, Germany, 25 - 30 Apr 2022, pp.044
DOI	10.22323/1.416.0044
Subject category	hep-th ; Particle Physics - Theory ; hep-ph ; Particle Physics - Phenomenology
Abstract	The high-energy limit of $2\to 2$ scattering amplitudes offers an excellent setting to explore the universal features of gauge theories. At Leading Logarithmic (LL) accuracy the partonic amplitude is governed by Regge poles in the complex angular momentum plane. Beyond LL, Regge cuts in this plane begin to play an important role. Specifically, the real part of the amplitude at Next-to-Next-to-Leading Logarithmic (NNLL) accuracy presents for the first time both a Regge pole and a Regge cut. Analysing this tower of logarithms and computing it explicitly through four loops we are able to systematically separate between the Regge pole and the Regge cut. The former involves two fundamental parameters, namely the gluon Regge trajectory and impact factors. We explain how to consistently define the impact factors at two loops and the Regge trajectory at three loops. We confirm that the singularities of the trajectory are given by the cusp anomalous dimension. We also show that the Regge-cut contribution at four loop is nonplanar.
Copyright/License	preprint: (License: CC BY 4.0) publication: © 2022-2025 The author(s) (License: CC-BY-NC-ND-4.0)

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