Helac-Nlo

124

We present a comprehensive study of differential distributions for Tevatron top-pair events at the level of stable top quarks. All calculations are performed in NNLO QCD with the help of a fully differential partonic Monte-Carlo and are exact at this order in perturbation theory. We present predictions for all kinematic distributions for which data exists. Particular attention is paid on the top-quark forward-backward asymmetry which we study in detail. We compare the NNLO results with existing approximate NNLO predictions as well as differential distributions computed with different parton distribution sets. Theory errors are significantly smaller than current experimental ones with overall agreement between theory and data.

Section: P T Tt Distribution and Differential Asymmetrysupporting

confidence: 78%

Section: Details Of the Calculationmentioning

confidence: 99%

NNLO QCD predictions for fully-differential top-quark pair production at the Tevatron

Czakon

Fiedler

Heymes

et al. 2016

124

“…Today, 2 → 4 processes at next-to-leading order (NLO) are state of the art [1][2][3][4][5], and even higher multiplicities are affordable [6]. Several tools for the automated calculation of NLO differential cross sections are available [7,8], including the merging with parton showers [9]. There has been also a lot of advances in next-to-next-to-leading order (NNLO) calculations [10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

On the singular behaviour of scattering amplitudes in quantum field theory

Buchta

Chachamis

Draggiotis

et al. 2014

Abstract:We analyse the singular behaviour of one-loop integrals and scattering amplitudes in the framework of the loop-tree duality approach. We show that there is a partial cancellation of singularities at the loop integrand level among the different components of the corresponding dual representation that can be interpreted in terms of causality. The remaining threshold and infrared singularities are restricted to a finite region of the loop momentum space, which is of the size of the external momenta and can be mapped to the phase-space of real corrections to cancel the soft and collinear divergences.

“…In the past years, many groups have concentrated their efforts to make NLO calculations feasible, and a lot of codes have been designed [3][4][5][6][7][8][9][10][11] with a high level of automatisation and impressive performances, however with their range of applicability mostly restricted to the QCD sector of the SM. For EW corrections, the situation is more involved and a complete automatisation has not been achieved yet, while different groups are working in this direction [12,13].…”

Section: Jhep01(2015)094mentioning

confidence: 99%

Electroweak corrections to lepton pair production in association with two hard jets at the LHC

Denner

Hofer

Scharf

et al. 2015

Abstract:We compute the next-to-leading order corrections of O α 2 s α 3 to the hadronic production of two oppositely charged leptons and two hard jets, pp → jjℓ − ℓ + , using Recola and Collier. We include electroweak and QCD corrections at the given order and all off-shell effects. We provide detailed predictions for the LHC operating at 13 TeV and obtain per-cent-level corrections for the total cross section. For differential distributions we find significant non-uniform distortions in high-energy tails at the level of several ten per cent due to electroweak Sudakov logarithms and deformations at the level of a few per cent for angular variables.