Comparative study of various algorithms for the merging of parton showers and matrix elements in hadronic collisions

By Johan Alwall, S. Höche, F. Krauss, N. Lavesson, L. Lonnblad, Fabio Maltoni, M. Mangano, M. Moretti, Costas G. Papadopoulos, F. Piccinini and 4 more. 2007

1,250 citations recorded by the source corpus.

We compare different procedures for combining fixed-order tree-level matrix-element generators with parton showers. We use the case of W-production at the Tevatron and the LHC to compare different implementations of the so-called CKKW and MLM schemes using different matrix-element generators and different parton cascades. We find that although similar results are obtained in all cases, there are important differences.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/579d3e5f9ebbf05224341cab3e7f3424887fb537

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In Nuclear and High Energy Physics

Citations in the corpus

Search for supersymmetry in proton-proton collisions at 13 TeV in final states with jets and missing transverse momentum (2019, background): “2 [55, 56] event generator with leading order (LO) precision.”
Giant QCD K-factors beyond NLO (2010, background): “There is a close connection between ¯ nLO (or ¯¯ nLO) and CKKW and MLM [26, 53 ] matching, since they also both provide ways of combining tree-level results with different multiplicities.”
Effective field theory analysis of double Higgs boson production via gluon fusion (2015, methodology): “Zh have been matched up to one additional jet via the kT-jet MLM matching [36] to partially account for NLO effects.”
MadGraph/MadEvent v4: The New Web Generation (2007, methodology): “testing ground for matching procedures; there is a simple “central” 2 → 1 process, there is a hard scale set by the mass of the vector boson, and there is data from the Tevatron to compare to. A comparison between several implementations of matrix element–parton shower matching of W + jets productio”
Towards jetography (2009, background): “lead to extra jets) and which ones should come from the parton showers (those that don’t) [13, 14].”
Les Houches 2015: Physics at TeV Colliders Standard Model Working Group Report (2016, methodology): “The events are generated with the CTEQ6L1 [189] parton distribution functions, and the ktMLM matching scheme [320] with a matching parameter of 20 GeV is applied.”
Phenomenology of event shapes at hadron colliders (2010, methodology): “We use the MLM prescription [105] to avoid double counting between emissions generated in the hard 2 → n scattering and those generated by the parton shower.”
Extraction and validation of a new set of CMS pythia8 tunes from underlying-event measurements (2019, methodology): “The procedures considered in this paper are the “FxFx” [38] or the “POWHEG” [39] methods for merging higher-order (NLO) MEs to PS and the “MLM” method [31].”
Search for invisible decays of a Higgs boson produced through vector boson fusion in proton-proton collisions at $\sqrt{s} =$ 13 TeV (2018, methodology): “In the case of LO (NLO) MADGRAPH5 aMC@NLO samples, partons from the matrix elements are matched to the parton shower description via the MLM [47] (FxFx [48]) scheme.”
Measurement of differential cross sections for top quark pair production using the lepton+jets final state in proton-proton collisions at 13 TeV (2016, methodology): “In one simulation all processes of up to three additional partons are calculated at leading order (LO) and combined with the PYTHIA8 parton shower simulation using the MLM [17] algorithm.”