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Related papers: On-Shell Unitarity Bootstrap for QCD Amplitudes

200 papers

We extend the generalized D-dimensional unitarity method for numerical evaluation of one-loop amplitudes by incorporating massive particles. The issues related to extending the spinor algebra to higher dimensions, treatment of external…

High Energy Physics - Phenomenology · Physics 2010-04-21 R. K. Ellis , W. T. Giele , Z. Kunszt , K. Melnikov

We calculate the one-loop QCD virtual corrections to all helicity amplitudes for parton level virtual Compton scattering processes. We include the amplitudes both on quark target process $\gamma^* q\to\gamma q$ and on gluon target process…

High Energy Physics - Phenomenology · Physics 2009-11-10 H. W. Huang , T. Morii

We combine the unitarity method with the six-dimensional helicity formalism of Cheung and O'Connell to construct loop-level scattering amplitudes. As a first example, we construct dimensionally regularized QCD one-loop four-point…

High Energy Physics - Theory · Physics 2015-03-17 Zvi Bern , John Joseph Carrasco , Tristan Dennen , Yu-tin Huang , Harald Ita

We review techniques for more efficient computation of perturbative scattering amplitudes in gauge theory, in particular tree and one-loop multi-parton amplitudes in QCD. We emphasize the advantages of (1) using color and helicity…

High Energy Physics - Phenomenology · Physics 2008-02-03 L. Dixon

Modelling non-linear activation functions on quantum computers is vital for quantum neurons employed in fully quantum neural networks, however, remains a challenging task. We introduce an amplitude-based implementation for approximating…

Quantum Physics · Physics 2023-02-09 Jonas Koppe , Mark-Oliver Wolf

We review some of the recent advances in the computation of one-loop scattering amplitudes which led to the construction of efficient and automated computational tools for NLO predictions. Particular attention is devoted to unitarity-based…

High Energy Physics - Phenomenology · Physics 2015-06-17 Giovanni Ossola

In this talk we describe the recursive Approach to One-loop QCD Matrix Elements.

High Energy Physics - Phenomenology · Physics 2009-11-11 N. E. J. Bjerrum-Bohr , David C. Dunbar , Harald Ita

I provide a basic introduction to modern helicity amplitude methods, including color organization, the spinor helicity formalism, and factorization properties. I also describe the BCFW (on-shell) recursion relation at tree level, and…

High Energy Physics - Phenomenology · Physics 2015-06-02 Lance J. Dixon

A precise understanding of LHC phenomenology requires the inclusion of one-loop corrections for multi-particle final states. In this talk we describe a semi-numerical method to compute one-loop amplitudes with many external particles and…

High Energy Physics - Phenomenology · Physics 2009-11-11 T. Binoth , M. Ciccolini , G. Heinrich

We describe a general method that enables us to obtain all the singular terms of helicity amplitudes of n-parton processes at one loop. The algorithm uses helicity amplitudes at tree level and simple color algebra. We illustrate the method…

High Energy Physics - Phenomenology · Physics 2009-10-28 Zoltan Kunszt , Adrian Signer , Zoltan Trocsanyi

We show that a well-known simple formula for the explicit infrared poles of one-loop QCD amplitudes has a corresponding simple counterpart in unintegrated form. The unintegrated formula approximates the integrand of one-loop QCD amplitudes…

High Energy Physics - Phenomenology · Physics 2010-05-25 Mohammad Assadsolimani , Sebastian Becker , Stefan Weinzierl

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

We present a novel set of Feynman rules and generalised unitarity cut-conditions for computing one-loop amplitudes via d-dimensional integrand reduction algorithm. Our algorithm is suited for analytic as well as numerical result, because…

High Energy Physics - Phenomenology · Physics 2015-05-25 W. J. Torres Bobadilla , A. R. Fazio , P. Mastrolia , E. Mirabella

We show how generalised unitarity cuts in D = 4 - 2 epsilon dimensions can be used to calculate efficiently complete one-loop scattering amplitudes in non-supersymmetric Yang-Mills theory. This approach naturally generates the rational…

High Energy Physics - Theory · Physics 2009-11-11 Andreas Brandhuber , Simon McNamara , Bill Spence , Gabriele Travaglini

We present the first numerical computation of two-loop amplitudes based on the unitarity method. As a proof of principle, we compute the four-gluon process. We discuss the new method, analyze its numerical properties and apply it to…

High Energy Physics - Phenomenology · Physics 2017-10-11 S. Abreu , F. Febres Cordero , H. Ita , M. Jaquier , B. Page , M. Zeng

Recent Developments in computing very specific helicity amplitudes in two loop QCD are presented. The techniques focus upon the singular structure of the amplitude rather than on a diagramatic and integration approach

High Energy Physics - Phenomenology · Physics 2017-12-15 David C. Dunbar , John H Godwin , Guy R. Jehu , Warren B. Perkins

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 describe techniques that simplify the calculation of one-loop QCD amplitudes with many external legs, which are needed for next-to-leading-order (NLO) corrections to multi-jet processes. The constraints imposed by perturbative unitarity,…

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

We develop the on-shell action formalism within Worldline Quantum Field Theory (WQFT) to describe scattering of spinning compact bodies in General Relativity in the post-Minkowskian (PM) expansion. The real on-shell action is constructed…

High Energy Physics - Theory · Physics 2025-11-17 Kays Haddad , Gustav Uhre Jakobsen , Gustav Mogull , Jan Plefka

We review recent developments in the calculation of QCD loop amplitudes with several external legs, and their application to next-to-leading order jet production cross-sections. When a number of calculational tools are combined together ---…

High Energy Physics - Phenomenology · Physics 2007-05-23 Z. Bern , L. Dixon , D. A. Kosower , A. Signer