Automatic generation of tree level helicity amplitudes

Stelzer, T.; Long, W.F.

doi:10.1016/0010-4655(94)90084-1

Cited by 825 publications

(926 citation statements)

References 6 publications

(5 reference statements)

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“…In Figure 6 we plot the numerical result obtained with Whizard [17] for the tree-level cross-section, and the successive effective-theory approximations. We used the fixed-width scheme in Whizard and checked that the results from the O'Mega [34], CompHep [18] and MadGraph [20] matrix elements agree within the numerical error of the Monte-Carlo integration. The large constant shift of about 100 fb by the N 1/2 LO correction from the hard region is clearly visible, but the NLO approximation is already close to the full Born calculation.…”

Section: Comparison To the Four-fermion Born Cross Sectionmentioning

confidence: 99%

“…Note that we have chosen to multiply not only the leading order, but also the electroweak correction to the hadronic decay by the factor δ QCD defined in (20). In the numerical results below we will resum the full NLO width (81) in the effective-theory propagator (10), that is we do not perform an expansion of the propagator in the perturbative corrections to the matching coefficient ∆.…”

Section: Input Parameters and Summation Of W -Width Correctionsmentioning

confidence: 99%

“…We construct the effective-theory expansion of the tree approximation to the four-fermion cross section in Section 3. Of course, this calculation can be done nearly automatically without any expansions with programs such as Whizard [17], CompHep [18,19] or MadEvent [20,21]. The purpose of this section is to demonstrate the convergence of the expansion towards the "exact" tree-level result, and to provide analytic expressions for those terms that form part of the NLO calculation near threshold.…”

Section: Introductionmentioning

confidence: 99%

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Four-fermion production near the W pair-production threshold

et al. 2008

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We perform a dedicated study of the four-fermion production process e − e + → µ −ν µ ud X near the W pair-production threshold in view of the importance of this process for a precise measurement of the W boson mass. Accurate theoretical predictions for this process require a systematic treatment of finite-width effects. We use unstable-particle effective field theory (EFT) to perform an expansion in the coupling constants, Γ W /M W , and the non-relativistic velocity v of the W boson up to next-to-leading order in Γ W /M W ∼ α ew ∼ v 2 . We find that the dominant theoretical uncertainty in M W is currently due to an incomplete treatment of initial-state radiation. The remaining uncertainty of the NLO EFT calculation translates into δM W ≈ 10 -15 MeV, and to about 5 MeV with additional input from the NLO four-fermion calculation in the full theory.

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Section: Comparison To the Four-fermion Born Cross Sectionmentioning

confidence: 99%

Section: Input Parameters and Summation Of W -Width Correctionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Four-fermion production near the W pair-production threshold

et al. 2008

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“…The tree-level amplitudes can 3 be generated with the help of the build tool based on MadGraph 4 [47,48] that is available in the POWHEG BOX [49]. For pp → ttH, we use the virtual amplitudes of [22][23][24][25] and adapt them to the format required by the POWHEG BOX.…”

Section: Methodsmentioning

confidence: 99%

Higgs boson production in association with top quarks in the POWHEG BOX

et al. 2015

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We present results from the analytic calculation of ttH hadronic production at Next-to-Leading Order in QCD interfaced with parton-shower Monte Carlo event generators in the POWHEG BOX framework. We consider kinematic distributions of the top quark and Higgs boson at the 8 TeV Large Hadron Collider and study the theoretical uncertainties due to specific choices of renormalization/factorization scales and parton-showering algorithms, namely PYTHIA and HERWIG. The importance of spin-correlations in the production and decay stages of a top/antitop quark is discussed on the example of kinematic distributions of leptons originating from the top/antitop decays.The corresponding code is now part of the public release of the POWHEG BOX.

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“…[25] and have been checked against results obtained with Madgraph [26]. The soft and collinear singularities are treated both in the dipole subtraction method following Ref.…”

Section: Calculational Detailsmentioning

confidence: 99%

Precision calculations for the Higgs decays H → ZZ/WW → 4 leptons

Bredenstein

Denner

Dittmaier

et al. 2006

Nuclear Physics B - Proceedings Supplements

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Extending earlier work, we provide predictions obtained with the Monte Carlo generator PROPHECY4f for the decays H → ZZ/WW → 4l including the complete electroweak O(α) corrections and some higher-order improvements. The gauge-boson resonances are described in the complex-mass scheme. Here, particular attention is paid to a comparison of different final states with identical charges, such as e + e − µ + µ − and µ + µ − µ + µ − .

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Automatic generation of tree level helicity amplitudes

Cited by 825 publications

References 6 publications

Four-fermion production near the W pair-production threshold

Four-fermion production near the W pair-production threshold

Higgs boson production in association with top quarks in the POWHEG BOX

Precision calculations for the Higgs decays H → ZZ/WW → 4 leptons

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