QCD Matrix Elements + Parton Showers

By S. Catani, F. Krauss, Bryan R. Webber, Ralf Kühn. 2001

1,285 citations recorded by the source corpus.

We propose a method for combining QCD matrix elements and parton showers in Monte Carlo simulations of hadronic flnal states in e + e i annihilation. The matrix element and parton shower domains are separated at some value yini of the jet resolution, deflned according to the kT-clustering algorithm. The matrix elements are modifled by Sudakov form factors and the parton showers are subjected to a veto procedure to cancel dependence on yini to next-to-leading logarithmic accuracy. The method provides a leading-order description of hard multi-jet conflgurations together with jet fragmentation, while avoiding the most serious problems of double counting. We present flrst results of an approximate implementation using the event generator APACIC++.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/1d17bb3f16671e2b261d54c4b1dd33acbfeb4494

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In Nuclear and High Energy Physics

Citations in the corpus

The ATLAS Simulation Infrastructure (2010, methodology): “Sherpa [26] is a generator written in C++ which implements the CKKW duplicate removal prescription [52] to match fixed-order QCD matrix elements to QCD showers.”
Towards jetography (2009, background): “lead to extra jets) and which ones should come from the parton showers (those that don’t) [13, 14].”
Extraction and validation of a new set of CMS pythia8 tunes from underlying-event measurements (2019, methodology): “Merging schemes, such as the kT–MLM [31] or CKKW [32, 33], allow the combination of predictions of jet production using ME calculations with those from PS emissions for soft and collinear parton radiation at leading-log accuracy without double counting or dead regions.”
Les Houches 2017: Physics at TeV Colliders Standard Model Working Group Report (2017, methodology): “Here, scales are set using the CKKW procedure [924,935].”
Merging H/W/Z + 0 and 1 jet at NLO with no merging scale: a path to parton shower + NNLO matching (2012, methodology): “A first question that we would like to consider is whether our MiNLO procedure downgraded to the LO level (that is to say, to the CKKW procedure [40] as applied to the inclusive sample), already achieves our goal at LO accuracy, that is to say, it is such that by integrating the softest emission one”
QCD matrix elements + parton showers. The NLO case (2012, methodology): “Alternatively, algorithms to merge various leading-order matrix elements with increasing parton multiplicity into one inclusive sample have been proposed [31–37].”
A perturbative framework for jet quenching (2012, background): “In principle, hard emissions could also be corrected to the full matrix elements using merging prescriptions such as [61, 62], but for the purpose of this study the accuracy of the parton shower is sufficient.”
Event generation with SHERPA 1.1 (2008, methodology): “All features needed for a consistent merging with matrix elements [19, 20] are included, however, the main part of the merging procedure is implemented in the SHERPA module itself.”
Soft triple-real radiation for Higgs production at N3LO (2013, neutral): “[15–35] See, for example, refs.”
Correcting the Colour-Dipole Cascade Model with Fixed Order Matrix Elements (2001, methodology): “This scale can be defined in many different ways, usually connected to a specific jet reconstruction algorithm which can be used both on the ME and on the finalstate hadrons observed in an experiment.”
Les Houches 2015: Physics at TeV Colliders Standard Model Working Group Report (2016, methodology): “the process obtained by the attempt to cluster a Wbb̄j event with a procedure similar to CKKW [245]) have been chosen as follows:”
Jet energy scale measurements and their systematic uncertainties in proton-proton collisions at √s=13 TeV with the ATLAS detector (2017, neutral): “Sherpa uses multileg 2→ N matrix elements that are matched to parton showers following the CKKW [27] prescription.”
Phenomenology of event shapes at hadron colliders (2010, methodology): “To gauge uncertainties in the resulting matched samples we shall simultaneously vary the renormalisation and factorisation scales in the tree-level matrix elements by a factor of two around their default settings in the MLM procedure (which are taken as in the CKKW procedure [106]).”