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We calculate the two-loop QCD corrections to $gg \to ZZ$ involving a closed top-quark loop. We present a new method to systematically construct linear combinations of Feynman integrals with a convergent parametric representation, where we…

High Energy Physics - Phenomenology · Physics 2021-06-16 Bakul Agarwal , Stephen P. Jones , Andreas von Manteuffel

We present the two-loop virtual QCD corrections to the scattering of massless identical quarks, q qbar to q qbar, in conventional dimensional regularisation and using the MSbar scheme. The structure of the infrared divergences agrees with…

High Energy Physics - Phenomenology · Physics 2008-11-26 C. Anastasiou , E. W. N. Glover , C. Oleari , M. E. Tejeda-Yeomans

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

We compute the leading colour contributions to five-gluon scattering at two loops in massless QCD. The integrands of all independent helicity amplitudes are evaluated using d-dimensional generalised unitarity cuts and finite field…

High Energy Physics - Phenomenology · Physics 2018-03-07 Simon Badger , Christian Brønnum-Hansen , Heribertus Bayu Hartanto , Tiziano Peraro

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 virtual QCD corrections to the scattering of massless distinct quarks in conventional dimensional regularisation. The structure of the infrared divergences agrees with that predicted by Catani while expressions for…

High Energy Physics - Phenomenology · Physics 2008-11-26 C. Anastasiou , E. W. N. Glover , C. Oleari , M. E. Tejeda-Yeomans

We compute the two-loop corrections to the helicity amplitudes for the coupling of a massive vector boson to a massless quark-antiquark pair and a gluon, accounting for vector and axial-vector couplings of the vector boson and…

High Energy Physics - Phenomenology · Physics 2023-06-19 Thomas Gehrmann , Tiziano Peraro , Lorenzo Tancredi

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 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 compute the two-loop QCD helicity amplitudes for the process e^+e^- --> q bar{q} g. The amplitudes are extracted in a scheme-independent manner from the coefficients appearing in the general tensorial structure for this process. The…

High Energy Physics - Phenomenology · Physics 2010-04-06 L. W. Garland , T. Gehrmann , E. W. N. Glover , A. Koukoutsakis , E. Remiddi

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 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

We complete the computation of the two-loop helicity amplitudes for the production of three photons at hadron colliders, including all contributions beyond the leading-color approximation. We reconstruct the analytic form of the amplitudes…

High Energy Physics - Phenomenology · Physics 2023-10-16 Samuel Abreu , Giuseppe De Laurentis , Harald Ita , Maximillian Klinkert , Ben Page , Vasily Sotnikov

We use an n-dimensional projection method to calculate helicity amplitudes for photon-photon scattering up to the two-loop level, for massless particles inside the loop. We confirm the recent standard model results found by Bern et al using…

High Energy Physics - Phenomenology · Physics 2009-11-07 T. Binoth , E. W. N. Glover , P. Marquard , J. J. van der Bij

Virtual two-loop corrections to scattering amplitudes are a key ingredient to precision physics at collider experiments. We compute the full set of planar master integrals relevant to five-point functions in massless QCD, and use these to…

High Energy Physics - Phenomenology · Physics 2016-04-18 T. Gehrmann , J. M. Henn , N. A. Lo Presti

We present the first numerical results for the two-loop helicity amplitudes for the scattering of four partons and a W-boson in QCD. We use a finite field sampling method to reduce directly from Feynman diagrams to the coefficients of a set…

High Energy Physics - Phenomenology · Physics 2019-07-01 Heribertus Bayu Hartanto , Simon Badger , Christian Brønnum-Hansen , Tiziano Peraro

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 the two-loop massless QCD corrections to the helicity amplitudes for the production of two massive vector bosons in quark-antiquark annihilation, allowing for an arbitrary virtuality of the vector bosons: $q \bar q' \to V_1V_2$.…

High Energy Physics - Phenomenology · Physics 2015-10-28 Thomas Gehrmann , Andreas von Manteuffel , Lorenzo Tancredi

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 helicity amplitudes for the processes $gg\to Zg$ and $gg\to Z\gamma$ to two loops in massless QCD. The perturbative expansion of these processes starts only at the one-loop level, such that our results are a crucial…

High Energy Physics - Phenomenology · Physics 2023-08-21 Thomas Gehrmann , Lorenzo Tancredi , Erich Weihs