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In this paper we discuss in detail computational methods and new results for one-loop virtual corrections to N = 4 super Yang-Mills scattering amplitudes calculated to all orders in epsilon, the dimensional regularization parameter. It is…

High Energy Physics - Theory · Physics 2015-03-19 Robert M. Schabinger

We calculate gauge theory one-loop amplitudes with the aid of the complex shift used in the Britto-Cachazo-Feng-Witten (BCFW) recursion relations of tree amplitudes. We apply the shift to the integrand and show that the contribution from…

High Energy Physics - Theory · Physics 2013-05-30 Savan Kharel , George Siopsis

We calculate a class of one-loop six-point amplitudes in the Yukawa model. The construction of multi-particle amplitudes is done in the string inspired formalism and compared to the Feynman diagrammatic approach. We show that there exists a…

High Energy Physics - Phenomenology · Physics 2009-11-07 T. Binoth , J. P. Guillet , G. Heinrich , C. Schubert

We have calculated the one-loop scattering amplitude of an electron by an external Coulomb potential in QED free of infrared divergences. This feature is achieved by applying the Faddeev-Kulish formalism, which implies a redefinition of…

High Energy Physics - Phenomenology · Physics 2024-11-15 J. A. Oller , Marcela Peláez

The massless 4-point one-loop amplitude computation in the pure spinor formalism is shown to agree with the computation in the RNS formalism.

High Energy Physics - Theory · Physics 2009-11-11 Carlos R. Mafra

Scattering amplitudes for the massless QCD process, $q\bar{q}\to q^\prime\bar{q}^\prime$, are calculated in the one-loop order in the Feynman-Diagram (FD) gauge, where gluons are quantized on the light cone with opposite direction of the…

High Energy Physics - Phenomenology · Physics 2024-07-17 Kaoru Hagiwara , Kentarou Mawatari , Youichi Yamada , Ya-Juan Zheng

From the graviton-graviton scattering amplitudes calculated perturbatively in quantum gravity to the one-loop order, we develop further a formalism that allows one to calculate infrared-finite partial-wave amplitudes fulfilling perturbative…

High Energy Physics - Theory · Physics 2025-01-22 J. A. Oller , Marcela Peláez

We present an overview of techniques developed in recent years for the efficient calculation of one-loop multiparton amplitudes, in particular those relying on unitarity and collinear factorization.

High Energy Physics - Phenomenology · Physics 2009-10-30 Zvi Bern , Lance Dixon , David C. Dunbar , David A. Kosower

The recently developed on-shell bootstrap for computing one-loop amplitudes in non-supersymmetric theories such as QCD combines the unitarity method with loop-level on-shell recursion. For generic helicity configurations, the recursion…

High Energy Physics - Phenomenology · Physics 2008-11-26 Carola F. Berger , Zvi Bern , Lance J. Dixon , Darren Forde , David A. Kosower

For three dimensional N=6 superconformal field theories we compute one-loop scattering amplitudes for any number of external particles. We focus on a particular subsector of N=2 invariant superamplitudes for which the ordinary perturbative…

High Energy Physics - Theory · Physics 2012-07-11 Marco S. Bianchi , Matias Leoni , Andrea Mauri , Silvia Penati , Alberto Santambrogio

We review the Four-Dimensional-Formulation variant of the Four-Dimensional-Helicity scheme, by showing two applications of this regularisation scheme. The first one is the computation of one-loop helicity amplitudes, for which we present…

High Energy Physics - Phenomenology · Physics 2016-01-22 William J. Torres Bobadilla

We present a semi-recursive method for calculating the rational parts of one-loop gravity amplitudes which utilises axial gauge diagrams to determine the non-factorising pieces of the amplitude. This method is used to compute the one-loop…

High Energy Physics - Theory · Physics 2014-11-20 David C. Dunbar , James H. Ettle , Warren B. Perkins

An efficient numerical algorithm to evaluate one-loop amplitudes using tensor integrals is presented. In particular, it is shown by explicit calculations that for ordered QCD amplitudes with a number of external legs up to 10, its…

High Energy Physics - Phenomenology · Physics 2009-08-11 A. van Hameren

We review progress in calculating one-loop scattering amplitudes required for next-to-leading-order corrections to QCD processes. The underlying technical developments include the spinor helicity formalism, color decompositions,…

High Energy Physics - Phenomenology · Physics 2010-11-15 Z. Bern , L. Dixon , D. A. Kosower

We review recent progress on the calculation of scattering amplitudes in the high-energy limit. We start by illustrating the shockwave formalism, which allows one to calculate amplitudes as iterated solutions of rapidity evolution…

High Energy Physics - Phenomenology · Physics 2021-11-10 Leonardo Vernazza , Giulio Falcioni , Einan Gardi , Niamh Maher , Calum Milloy

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 introduce a novel construction of a contour deformation within the framework of Loop-Tree Duality for the numerical computation of loop integrals featuring threshold singularities in momentum space. The functional form of our contour…

High Energy Physics - Phenomenology · Physics 2020-11-24 Zeno Capatti , Valentin Hirschi , Dario Kermanschah , Andrea Pelloni , Ben Ruijl

In this review, we discuss recent developments concerning efficient calculations of multi-loop multi-leg scattering amplitudes. Inspired by the remarkable properties of the Loop-Tree Duality (LTD), we explain how to reconstruct an integrand…

High Energy Physics - Phenomenology · Physics 2021-09-30 German F. R. Sborlini

We review recent progress in calculations of one-loop QCD amplitudes. By imposing the consistency requirements of unitarity and correct behavior as the momenta of two legs become collinear, we construct ansatze for one-loop amplitudes with…

High Energy Physics - Phenomenology · Physics 2008-02-03 Z. Bern , L. Dixon , D. Dunbar , D. A. Kosower

We present a semi-numerical method to compute one-loop corrections to multi-leg processes. We apply the method to the study of Higgs plus four parton and six gluon amplitudes.

High Energy Physics - Phenomenology · Physics 2007-05-23 G. Zanderighi