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Related papers: Two-loop splitting functions in QCD

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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

We present a calculation of the helicity amplitudes for the process $gg\to\gamma\gamma$ in three-loop massless QCD. We employ a recently proposed method to calculate scattering amplitudes in the 't Hooft-Veltman scheme that reduces the…

High Energy Physics - Phenomenology · Physics 2022-04-05 Piotr Bargiela , Fabrizio Caola , Andreas von Manteuffel , Lorenzo Tancredi

We present a method for the computation of hepta-cuts of two loop scattering amplitudes. Four dimensional unitarity cuts are used to factorise the integrand onto the product of six tree-level amplitudes evaluated at complex momentum values.…

High Energy Physics - Phenomenology · Physics 2012-04-18 Simon Badger , Hjalte Frellesvig , Yang Zhang

We present the first benchmark evaluation of the two-loop finite remainders for the production of a top-quark pair in association with a jet at hadron colliders in the gluon channel. We work in the leading colour approximation, and perform…

High Energy Physics - Phenomenology · Physics 2025-03-14 Simon Badger , Matteo Becchetti , Colomba Brancaccio , Heribertus Bayu Hartanto , Simone Zoia

Two-loop four-gluon N=4 susy amplitudes are evaluated via cutting techniques as a testing ground for QCD. A conjecture for four-point amplitudes to all loop orders is described. We also present a new conjecture for the leading-color part of…

High Energy Physics - Phenomenology · Physics 2009-10-30 Z. Bern , J. Rozowsky , B. Yan

The computation of two-loop amplitudes for the production of multiple Higgs and electroweak gauge bosons via gluon fusion with exact dependence on quark masses relies primarily on numerical methods. We propose a framework that enables their…

High Energy Physics - Phenomenology · Physics 2024-11-13 Charalampos Anastasiou , Julia Karlen , George Sterman , Aniruddha Venkata

We have computed the even-$N$ moments $N \leq 20$ of the gluon-to-quark splitting function $P_{\rm qg}$ at the fourth order of perturbative QCD via the renormalization of off-shell operator matrix elements. Our results, derived analytically…

High Energy Physics - Phenomenology · Physics 2024-04-16 G. Falcioni , F. Herzog , S. Moch , A. Vogt

We analytically calculate one- and two-loop helicity amplitudes in massless QED, by adopting a four-dimensional tensor decomposition. We draw our attention to four-fermion and Compton scattering processes to higher orders in the dimensional…

High Energy Physics - Phenomenology · Physics 2024-11-20 Thomas Dave , William J. Torres Bobadilla

High-energy factorization of 2 -> 2 amplitudes in QCD has been recently pushed to the next-to-next-to-leading logarithmic order by determining the three-loop gluon Regge trajectory. This was based on computing multi-Reggeon exchanges using…

High Energy Physics - Phenomenology · Physics 2024-12-31 Samuel Abreu , Giuseppe De Laurentis , Giulio Falcioni , Einan Gardi , Calum Milloy , Leonardo Vernazza

We compute the two-loop QCD corrections to $q g \to H q$ and $q \bar{q} \to H g$ amplitudes mediated by loops of nearly massless quarks. These amplitudes provide the last missing ingredient required to compute the NLO QCD corrections to the…

High Energy Physics - Phenomenology · Physics 2017-03-22 Kirill Melnikov , Lorenzo Tancredi , Christopher Wever

We compute the two-loop helicity amplitudes for the production of three photons at hadron colliders in QCD at leading-color. Using the two-loop numerical unitarity method coupled with analytic reconstruction techniques, we obtain the…

High Energy Physics - Phenomenology · Physics 2021-01-20 S. Abreu , B. Page , E. Pascual , V. Sotnikov

We present the two-loop helicity amplitudes for the scattering of two gluons into two gluons in QCD, which are relevant for next-to-next-to-leading order corrections to jet production at hadron colliders. We give the results in the `t…

High Energy Physics - Phenomenology · Physics 2010-04-06 Zvi Bern , Abilio De Freitas , Lance Dixon

We calculate the unpolarized twist-2 three-loop splitting functions $P_{qg}^{(2)}(x)$ and $P_{gg}^{(2,\rm N_F)}(x)$ and the associated anomalous dimensions using massive three-loop operator matrix elements. While we calculate…

High Energy Physics - Phenomenology · Physics 2017-08-23 J. Ablinger , A. Behring , J. Blümlein , A. De Freitas , A. von Manteuffel , C. Schneider

We present a new method for computing multi-loop scattering amplitudes in Quantum Field Theory. It extends the Generalized Unitarity method by constraining not only the integrand of the amplitude but also its full integrated form. Our…

High Energy Physics - Theory · Physics 2025-12-18 Piotr Bargiela

We calculate all planar contributions to the two-loop massless helicity amplitudes for the process $q\bar q\to \gamma\gamma\gamma$. The results are presented in fully analytic form in terms of the functional basis proposed recently by…

High Energy Physics - Phenomenology · Physics 2021-08-25 Herschel A. Chawdhry , Michal Czakon , Alexander Mitov , Rene Poncelet

We use the solutions to the recursion relations for double-off-shell fermion currents to compute helicity amplitudes for $n$-photon scattering and electron-positron annihilation to photons in the massless limit of QED. The form of these…

High Energy Physics - Phenomenology · Physics 2009-10-22 Gregory Mahlon

We compute two-loop helicity amplitudes in QCD for diphoton production through quark- and gluon-initiated channels, accounting for a massive internal quark loop by keeping its full mass dependence. Using physical projectors, we directly…

High Energy Physics - Phenomenology · Physics 2025-02-06 Taushif Ahmed , Amlan Chakraborty , Ekta Chaubey , Mandeep Kaur

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 present the first full analytic evaluation of the scattering amplitude for the process $q {\bar q} \to Q {\bar Q}$ up-to two loops in Quantum Chromodynamics, for a massless $(q)$ and a massive $(Q)$ quark flavour. The interference terms…

High Energy Physics - Phenomenology · Physics 2022-09-28 Manoj K. Mandal , Pierpaolo Mastrolia , Jonathan Ronca , William J. Torres Bobadilla

We provide results for the one-loop triple-collinear color/spin-space splitting operators for the five possible processes, $q \to qq'\bar{q}'$, $q \to qq\bar{q}$, $q \to qgg$, $g \to gq\bar{q}$ and $g \to ggg$. The expressions are exact in…

High Energy Physics - Phenomenology · Physics 2022-07-11 Michał Czakon , Sebastian Sapeta