Helac-Phegas: A generator for all parton level processes

Cafarella, Alessandro; Papadopoulos, Costas G.; Worek, Małgorzata

doi:10.1016/j.cpc.2009.04.023

Cited by 171 publications

(143 citation statements)

References 49 publications

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“…Each of these has its strengths and may be appropriate for particular kinds of calculations. Among the multi-purpose matrix element generators are CalcHep [1][2][3][4], FeynArts/FormCalc [5][6][7][8][9], Helac [10,11], MadGraph [12][13][14][15][16], Sherpa [17,18] and Whizard [19,20]. The parton-level collision is often followed by the important step of radiation and hadronization by packages such as Herwig [21][22][23][24], Pythia [25][26][27] and Sherpa.…”

Section: Introductionmentioning

confidence: 99%

FeynRules 2.0 — A complete toolbox for tree-level phenomenology

Alloul

Christensen

Degrande

et al. 2014

Computer Physics Communications

2,355

1,904

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FeynRules is a Mathematica-based package which addresses the implementation of particle physics models, which are given in the form of a list of fields, parameters and a Lagrangian, into high-energy physics tools. It calculates the underlying Feynman rules and outputs them to a form appropriate for various programs such as CalcHep, FeynArts, MadGraph, Sherpa and Whizard. Since the original version, many new features have been added: support for two-component fermions, spin-3/2 and spin-2 fields, superspace notation and calculations, automatic mass diagonalization, completely general FeynArts output, a new universal FeynRules output interface, a new Whizard interface, automatic 1 → 2 decay width calculation, improved speed and efficiency, new guidelines for validation and a new web-based validation package. With this feature set, FeynRules enables models to go from theory to simulation and comparison with experiment quickly, efficiently and accurately.

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Section: Introductionmentioning

confidence: 99%

FeynRules 2.0 — A complete toolbox for tree-level phenomenology

Alloul

Christensen

Degrande

et al. 2014

Computer Physics Communications

2,355

1,904

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“…To this end, we have generated an inclusive parton-level sample of pp → ttjj where j stands for u, d, c, s, b or g. The event sample has been produced with Helac-Phegas [34][35][36] in the Les Houches event file format [37] and interfaced with the general purpose Monte Carlo program Pythia 6.4 (version 6.427) [38] to include initial-and final-state shower effects. We simulate pp collisions at √ s = 8 TeV using the following parton level cuts,…”

Section: Leading Order Results With Parton Showermentioning

confidence: 99%

On the ratio of t t ¯ b b ¯ $$ t\overline{t} b\overline{b} $$ and t t ¯ jj $$ t\overline{t} jj $$ cross sections at the CERN Large Hadron Collider

Bevilacqua

Worek

2014

J. High Energ. Phys.

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Triggered by ongoing experimental analyses, we report on a study of the cross section ratio σ(pp → ttbb)/σ(pp → ttjj) at the next-to-leading order in QCD, focusing on both present and future collider energies: √ s = 7, 8, 13 TeV. In particular, we provide a comparison between our predictions and the currently available CMS data for the 8 TeV run. We further analyse the kinematics and scale uncertainties of the two processes for a single set of parton distribution functions, with the goal of assessing possible correlations that might help to reduce the theoretical error of the ratio and thus enhance the predictive power of this observable. We argue that the different jet kinematics makes the ttbb and ttjj processes uncorrelated in several observables, and show that the scale uncertainty is not significantly reduced when taking the ratio of the cross sections.

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“…Most noticeably, the NLL function g (δ,B) 2 receives a new contribution coming from correlated gluon emission. 5 Because of their soft and large-angle nature, non-global logarithms have a complicated color structure. However, for phenomenological purposes, their resummation can be performed in the large-N C limit [111,112,114,115], thus trivializing the color structure again.…”

Section: Jhep02(2015)106mentioning

confidence: 99%

“…(3.3). An explicit 5 We should mention that the particular choice of the algorithm used to define jets can influence the resummation structure at the level of g (δ,B)…”

Section: Automated Matchingmentioning

confidence: 99%

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Soft evolution of multi-jet final states

Gerwick

Schumann

Höche

et al. 2015

J. High Energ. Phys.

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We present a new framework for computing resummed and matched distributions in processes with many hard QCD jets. The intricate color structure of soft gluon emission at large angles renders resummed calculations highly non-trivial in this case. We automate all ingredients necessary for the color evolution of the soft function at next-toleading-logarithmic accuracy, namely the selection of the color bases and the projections of color operators and Born amplitudes onto those bases. Explicit results for all QCD processes with up to 2 → 5 partons are given. We also devise a new tree-level matching scheme for resummed calculations which exploits a quasi-local subtraction based on the Catani-Seymour dipole formalism. We implement both resummation and matching in the Sherpa event generator. As a proof of concept, we compute the resummed and matched transverse-thrust distribution for hadronic collisions.

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Helac-Phegas: A generator for all parton level processes

Cited by 171 publications

References 49 publications

FeynRules 2.0 — A complete toolbox for tree-level phenomenology

FeynRules 2.0 — A complete toolbox for tree-level phenomenology

On the ratio of t t ¯ b b ¯ $$ t\overline{t} b\overline{b} $$ and t t ¯ jj $$ t\overline{t} jj $$ cross sections at the CERN Large Hadron Collider

Soft evolution of multi-jet final states

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