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The infrared structure of (multi-loop) scattering amplitudes is determined entirely by the identities of the external particles participating in the scattering. The two-loop infrared structure of pure \qcd\ amplitudes has been known for…

High Energy Physics - Phenomenology · Physics 2015-06-16 William B. Kilgore

In this note, we propose a factorization formula for gauge-theory scattering amplitudes up to two loops in the high-energy boosted limit. Our formula extends existing results in the literature by incorporating the contributions from massive…

High Energy Physics - Phenomenology · Physics 2023-12-20 Guoxing Wang , Tianya Xia , Li Lin Yang , Xiaoping Ye

An exact formula is derived for the infrared singularities of dimensionally regularized scattering amplitudes in massless QCD with an arbitrary number of legs, valid at any number of loops. It is based on the conjecture that the…

High Energy Physics - Phenomenology · Physics 2013-10-23 Thomas Becher , Matthias Neubert

The high-energy factorization of gauge theory scattering amplitudes in terms of universal impact factors and a Reggeized exchange in the $t$-channel, corresponding to a Regge pole in the angular momentum plane, is know to conflict with the…

High Energy Physics - Phenomenology · Physics 2013-12-19 Vittorio Del Duca , Giulio Falcioni , Lorenzo Magnea , Leonardo Vernazza

We show how to extract the coefficients of the 4-, 3-, 2- and 1-point one-loop scalar integrals from the full one-loop amplitude of arbitrary scattering processes. In a similar fashion, also the rational terms can be derived. Basically no…

High Energy Physics - Phenomenology · Physics 2008-11-26 Giovanni Ossola , Costas G. Papadopoulos , Roberto Pittau

We suggest a new approach for the automatic and fully numerical evaluation of one-loop scattering amplitudes in perturbative quantum field theory. We use suitably formulated dispersion relations to perform the calculation as a convolution…

High Energy Physics - Phenomenology · Physics 2008-09-29 M. Moretti , F. Piccinini , A. D. Polosa

We compute all helicity amplitudes for the scattering of five partons in two-loop QCD in all the relevant flavor configurations, retaining all contributing color structures. We employ tensor projection to obtain helicity amplitudes in the…

High Energy Physics - Phenomenology · Physics 2023-12-01 Bakul Agarwal , Federico Buccioni , Federica Devoto , Giulio Gambuti , Andreas von Manteuffel , Lorenzo Tancredi

We present the two-loop pure gauge contribution to the gluon-gluon scattering amplitude with maximal helicity violation. Our construction of the amplitude does not rely directly on Feynman diagrams, but instead uses its analytic properties…

High Energy Physics - Phenomenology · Physics 2011-06-27 Z. Bern , L. Dixon , D. A. Kosower

This article reviews on-shell methods for analytic computation of loop amplitudes, emphasizing techniques based on unitarity cuts. Unitarity techniques are formulated generally but have been especially useful for calculating one-loop…

High Energy Physics - Theory · Physics 2015-05-20 Ruth Britto

We present the calculation of three-loop massless QCD and QED helicity amplitudes for light-by-light scattering. We make use of Lorentz tensor decomposition in the 't Hooft-Veltman dimensional regularisation scheme to reduce the complexity…

High Energy Physics - Phenomenology · Physics 2026-03-25 Piotr Bargiela , Amlan Chakraborty , Giulio Gambuti , Melih A. Ozcelik

Using rapidity evolution equations we study two-to-two gauge-theory scattering amplitudes in the Regge limit. We carry out explicit computations at next-to-next-to-leading logarithmic accuracy through four loops and present new results for…

High Energy Physics - Phenomenology · Physics 2022-03-30 Giulio Falcioni , Einan Gardi , Niamh Maher , Calum Milloy , Leonardo Vernazza

Generalised unitarity techniques are used to calculate the coefficients of box and triangle integral functions of one-loop gluon scattering amplitudes in gauge theories with $N < 4$ supersymmetries. We show that the box coefficients in N=1…

High Energy Physics - Theory · Physics 2008-11-26 Steven J. Bidder , N. E. J. Bjerrum-Bohr , David C. Dunbar , Warren B. Perkins

We compute the three-loop scattering amplitude of four gravitons in ${\mathcal N}=8$ supergravity. Our results are analytic formulae for a Laurent expansion of the amplitude in the regulator of dimensional regularisation. The coefficients…

High Energy Physics - Theory · Physics 2019-05-22 Johannes M. Henn , Bernhard Mistlberger

We determine the complete three-loop QCD soft anomalous dimension for multileg amplitudes involving a single massive coloured particle and any number of massless ones. This is achieved by applying a novel strategy based on a lightcone…

High Energy Physics - Phenomenology · Physics 2025-11-03 Einan Gardi , Zehao Zhu

We present a new method for computing complete one-loop amplitudes, including their rational parts, in non-supersymmetric gauge theory. This method merges the unitarity method with on-shell recursion relations. It systematizes a…

High Energy Physics - Phenomenology · Physics 2010-11-15 Zvi Bern , Lance J. Dixon , David A. Kosower

A closed formula is obtained for the infrared singularities of dimensionally regularized, massless gauge-theory scattering amplitudes with an arbitrary number of legs and loops. It follows from an all-order conjecture for the…

High Energy Physics - Phenomenology · Physics 2013-10-23 Thomas Becher , Matthias Neubert

The infrared divergences of QCD scattering amplitudes can be derived from an anomalous dimension \Gamma, which is a matrix in color space and depends on the momenta and masses of the external partons. It has recently been shown that in…

High Energy Physics - Phenomenology · Physics 2009-11-19 Andrea Ferroglia , Matthias Neubert , Ben D. Pecjak , Li Lin Yang

We study the factorisation properties of one-loop scattering amplitudes in the triple collinear limit and extract the universal splitting amplitudes for processes initiated by a gluon. The splitting amplitudes are derived from the analytic…

High Energy Physics - Phenomenology · Physics 2015-07-20 Simon Badger , Francesco Buciuni , Tiziano Peraro

Splitting amplitudes are universal functions governing the collinear behavior of scattering amplitudes for massless particles. We compute the two-loop g -> gg splitting amplitudes in QCD, N=1, and N=4 super-Yang-Mills theories, which…

High Energy Physics - Phenomenology · Physics 2010-03-25 Zvi Bern , Lance J. Dixon , David A. Kosower

The high-energy scattering amplitude of two colour-singlet quark-antiquark pairs is governed by the correlation function of two Wilson loops, which follow the classical straight lines for quark (antiquark) trajectories. This quantity is…

High Energy Physics - Phenomenology · Physics 2009-11-10 E. Meggiolaro