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We describe recent evaluations of three-loop vertex corrections which have been performed in the context of different physical applications: the massless quark and gluon form factor, the vector current matching coefficient between QCD and…

High Energy Physics - Phenomenology · Physics 2010-01-19 Matthias Steinhauser

We evaluate, in the high-energy limit, $s\gg|t|\gg m^2\gg\lambda^2$, the sum of amplitudes corresponding to a class of Feynman diagrams describing two-loop virtual photonic corrections to Bhabha scattering. The diagrams considered are box…

High Energy Physics - Phenomenology · Physics 2009-10-22 Göran Fäldt , Per Osland

The three-loop QCD contributions to the vacuum polarization functions of the $Z$ and $W$ bosons at zero momentum are calculated. The top quark is considered to be massive and the other quarks massless. Using these results, we calculate the…

High Energy Physics - Phenomenology · Physics 2011-01-13 L. Avdeev , J. Fleischer , S. Mikhailov , O. Tarasov

We compute the two-loop helicity amplitudes for the scattering of five gluons, including all contributions beyond the leading-color approximation. The analytic expressions are represented as linear combinations of transcendental functions…

High Energy Physics - Phenomenology · Physics 2024-05-15 Giuseppe De Laurentis , Harald Ita , Maximillian Klinkert , Vasily Sotnikov

We apply the supergraph with spurion technique to compute the renormalization of one-loop diagrams that contributes to electron and selectron self energies in a softly broken Supersymmetric Quantum Electrodynamics (SQED). In particular, we…

High Energy Physics - Phenomenology · Physics 2008-11-25 Tino S. Nyawelo , Paolo Gondolo

In this paper we consider the matching coefficients up to two loops between Quantum Chromodynamics (QCD) and Non-Relativistic QCD (NRQCD) for the vector, axial-vector, scalar and pseudo-scalar currents. The structure of the effective theory…

High Energy Physics - Phenomenology · Physics 2009-11-11 B. A. Kniehl , A. Onishchenko , J. H. Piclum , M. Steinhauser

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

I present the computation of the two-loop amplitudes for the scattering of a lepton pair with an off-shell and an on-shell photon in massless QED. We apply modern techniques developed to tackle QCD amplitudes with many scales: we express…

High Energy Physics - Phenomenology · Physics 2024-05-15 Simone Zoia

The decay B_s -> mu^+ mu^- in the Standard Model is generated by the well-known W-box and Z-penguin diagrams that give rise to an effective quark-lepton operator Q_A at low energies. We compute QCD corrections of order alpha_s^2 to its…

High Energy Physics - Phenomenology · Physics 2014-03-18 Thomas Hermann , Mikolaj Misiak , Matthias Steinhauser

We present results for the next-to-leading order QCD corrections to the production and semi-leptonic decays of a top quark pair in hadron collisions, retaining all spin correlations. To evaluate the virtual corrections, we employ…

High Energy Physics - Phenomenology · Physics 2009-11-18 Kirill Melnikov , Markus Schulze

Recently the two-loop next-to-leading logarithmic (NLL) virtual corrections to arbitrary processes with massless external fermions have been calculated. Within the spontaneously broken electroweak theory the one- and two-loop mass…

High Energy Physics - Phenomenology · Physics 2009-02-16 Bernd Jantzen

We present the leading-color two-loop QCD corrections for Higgs-boson production in association with two jets through gluon fusion in the heavy-top effective theory. We provide analytic expressions for the finite remainders of the helicity…

High Energy Physics - Phenomenology · Physics 2026-05-06 Giuseppe De Laurentis , Harald Ita , Viktor Kuschke , Michael Ruf , Vasily Sotnikov

We consider the Z Q Qbar vertex to second order in the QCD coupling for an on-shell massive quark-antiquark pair and for arbitrary momentum transfer of the Z boson. We present closed analytic expressions for the two parity-violating form…

High Energy Physics - Phenomenology · Physics 2010-04-05 W. Bernreuther , R. Bonciani , T. Gehrmann , R. Heinesch , T. Leineweber , P. Mastrolia , E. Remiddi

We present a determination of a new class of Feynman diagrams relevant for second-order QCD corrections to the top quark decay t -> b W. Modern computing techniques allow us to perform a reduction of the original loop integrals to master…

High Energy Physics - Phenomenology · Physics 2017-08-23 Maciej Slusarczyk

We consider the leading post-Newtonian and quantum corrections to the non-relativistic scattering amplitude of charged spin-1/2 fermions in the combined theory of general relativity and QED. The coupled Dirac-Einstein system is treated as…

General Relativity and Quantum Cosmology · Physics 2008-11-26 M. S. Butt

In this paper the complete two-loop corrections to the Higgs-boson decay, H -> gamma gamma, are presented. The evaluations of both QCD and electroweak corrections are based on a numerical approach. The results cover all kinematical regions,…

High Energy Physics - Phenomenology · Physics 2008-11-26 Giampiero Passarino , Christian Sturm , Sandro Uccirati

We use the worldline path integral approach to the Bern-Kosower formalism for extending this formalism to the calculation of higher order corrections to N - photon scattering. The case of the two-loop QED beta-function is considered in…

High Energy Physics - Phenomenology · Physics 2009-10-28 M. G. Schmidt , C. Schubert

We present a calculation of the NLO QCD corrections to the loop-induced production of a photon pair through gluon fusion, including massive top quarks at two loops. The two-loop virtual amplitudes are computed via projecting onto a set of…

High Energy Physics - Phenomenology · Physics 2019-12-13 Long Chen , Gudrun Heinrich , Stephan Jahn , Stephen P. Jones , Matthias Kerner , Johannes Schlenk , Hiroshi Yokoya

The Local Unitarity (LU) formalism provides a constructive, integrand-level realisation of the Kinoshita-Lee-Nauenberg (KLN) theorem, by combining loop and phase-space integrals appearing in scattering cross-sections in such a way that…

High Energy Physics - Phenomenology · Physics 2026-03-26 Zeno Capatti , Mathijs Fraaije , Valentin Hirschi , Lucien Huber , Ben Ruijl , Hua-Sheng Shao

In this study, we systematically calculate one-loop corrections to the Lorentz-violating vertices within the framework of CPT-odd Quantum Electrodynamics, encompassing scalar and photon fields in arbitrary gauge. Additionally, we ascertain…

High Energy Physics - Theory · Physics 2024-02-14 A. C. Lehum , J. R. Nascimento , A. Yu. Petrov