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Techniques based upon the string organisation of amplitudes may be used to simplify field theory calculations. We apply these techniques to perturbative gravity and calculate all one-loop amplitudes for four-graviton scattering with…

High Energy Physics - Theory · Physics 2009-10-28 David C. Dunbar , Paul S. Norridge

We review the current status of high-multiplicity double-virtual QCD corrections to processes relevant for LHC phenomenology. In particular, we discuss the recent full-color calculation of the five-parton process, whose two-loop amplitudes…

High Energy Physics - Phenomenology · Physics 2024-06-27 Giuseppe De Laurentis

We consider the multi-collinear limit of multi-gluon QCD amplitudes at tree level. We use the MHV rules for constructing colour ordered tree amplitudes and the general collinear factorisation formula to derive timelike splitting functions…

High Energy Physics - Phenomenology · Physics 2007-05-23 P. Marquard , T. G. Birthwright

We derive an ABDK-like relation between the one- and two-loop four-graviton amplitudes in N=8 supergravity. Specifically we show that the infrared divergent part of the two-loop amplitude is one-half the square of the one-loop amplitude,…

High Energy Physics - Theory · Physics 2008-11-26 Stephen G. Naculich , Horatiu Nastase , Howard J. Schnitzer

We detail the calculation of two-loop all-plus helicity amplitudes for pure Yang-Mills theory. The four dimensional unitarity methods and augmented recursion techniques we have developed, together with a knowledge of the singular structure…

High Energy Physics - Theory · Physics 2017-12-27 David C. Dunbar , John H. Godwin , Guy R. Jehu , Warren B. Perkins

We consider elastic quark-quark scattering at high energy and fixed transferred momentum. Performing factorization of soft gluon exchanges into Wilson lines vacuum expectation values and studying their properties, we find that the…

High Energy Physics - Phenomenology · Physics 2009-10-22 G. P. Korchemsky

We identify a large class of one-loop amplitudes for massless particles that can be constructed via unitarity from tree amplitudes, without any ambiguities. One-loop amplitudes for massless supersymmetric gauge theories fall into this…

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

Knowledge of two-loop QCD amplitudes for processes $q\bar q \to V_1 V_2 \to (l_1\bar l'_1)(l_2 \bar l'_2)$ is important for improving the theoretical description of four-lepton production in hadron collisions. In this paper we compute these…

High Energy Physics - Phenomenology · Physics 2015-06-22 Fabrizio Caola , Johannes M. Henn , Kirill Melnikov , Alexander V. Smirnov , Vladimir A. Smirnov

We present an analytic expression for the six-point all-plus helicity amplitude in QCD at two-loops. We compute the rational terms in a compact analytic form organised by their singularity structure.

High Energy Physics - Theory · Physics 2016-08-10 David C. Dunbar , Warren B. Perkins

A prescription is presented to construct manifestly gauge invariant tree-level scattering amplitudes with one or two off-shell initial-state gluons for processes with arbitrary particles in the final state, which allows for calculations…

High Energy Physics - Phenomenology · Physics 2013-07-09 A. van Hameren

Recently it has been proposed that gluon scattering amplitudes in gauge theory can be computed from the D-instanton expansion of the topological B-model on P^{3|4}, although only maximally helicity violating (MHV) amplitudes have so far…

High Energy Physics - Theory · Physics 2009-11-10 Radu Roiban , Marcus Spradlin , Anastasia Volovich

A powerful tool for calculations in non-Abelian gauge theories is obtained by combining the background field gauge, the helicity basis and the color decomposition methods. It has reproduced the one-loop calculation of the five-gluon…

High Energy Physics - Phenomenology · Physics 2009-10-31 Yoshiaki Yasui

This article brings together in a single place the different components of the six gluon one-loop amplitude

High Energy Physics - Phenomenology · Physics 2009-01-12 David C Dunbar

We present here the first result on the three-loop gluon jet function in perturbative QCD. Using the three-loop coefficient functions [1,2] for deep-inelastic scattering via the exchange of a virtual photon that couples to quarks or a…

High Energy Physics - Phenomenology · Physics 2018-11-28 Pulak Banerjee , Prasanna K. Dhani , V. Ravindran

We present a prescription to calculate manifestly gauge invariant tree-level helicity amplitudes for arbitrary scattering processes with off-shell initial-state gluons within the kinematics of high-energy scattering. We show that it is…

High Energy Physics - Phenomenology · Physics 2013-09-24 A. van Hameren , P. Kotko , K. Kutak

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

We present analytic results for the one-loop corrections of the helicity amplitudes of the QCD five-parton subprocesses involving four quarks and one gluon obtained with a standard Feynman diagram calculation using dimensional reduction.

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

The spectrum of coherent gluon radiation from a quark-anti-quark pair experiencing multiple scatterings within a coloured medium is central for understanding in-medium parton cascades. Despite its foundational importance, current results…

Gluon, ghost, and quark propagators are computed in the Schwinger-Dyson formalism. The full set of one-loop and two-loop contributions to the gap equations are evaluated for the first time. A new and efficient method for dealing with…

High Energy Physics - Phenomenology · Physics 2014-09-05 Joseph Meyers , Eric S. Swanson

The ability to calculate analytic full-colour two-to-three two-loop helicity amplitudes in massless QCD has been a recent triumph of the field, driving phenomenology towards one percent precision. In this contribution, we focus on the…

High Energy Physics - Phenomenology · Physics 2023-10-31 Ryan Moodie