Infrared singularities in QCD amplitudes

Gardi, E. and Magnea, L. (2009) Infrared singularities in QCD amplitudes. Il nuovo cimento C, 32 (5\6). pp. 137-157. ISSN 1826-9885

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Abstract

We review recent progress in determining the infrared singularity structure of on-shell scattering amplitudes in massless gauge theories. We present a simple ansatz where soft singularities of any scattering amplitude of massless partons, to any loop order, are written as a sum over colour dipoles, governed by the cusp anomalous dimension. We explain how this formula was obtained, as the simplest solution to a newly-derived set of equations constraining the singularity structure to all orders. We emphasize the physical ideas underlying this derivation: the factorization of soft and collinear modes, the special properties of soft gluon interactions, and the notion of the cusp anomaly. Finally, we briefly discuss potential multi-loop contributions going beyond the sum-over-dipoles formula, which cannot be excluded at present.

Item Type: Article
Uncontrolled Keywords: Gauge field theories ; Quantum chromodynamics ; Summation of perturbation theory
Subjects: 500 Scienze naturali e Matematica > 530 Fisica
Depositing User: Marina Spanti
Date Deposited: 27 Mar 2020 10:17
Last Modified: 27 Mar 2020 10:17
URI: http://eprints.bice.rm.cnr.it/id/eprint/16736

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