QCD matrix elements + parton showers. The NLO case

By S. Höche, F. Krauss, M. Schönherr, F. Siegert. Journal of High Energy Physics, 2012

1,054 citations recorded by the source corpus.

We present a process-independent technique to consistently combine next-to-leading order parton-level calculations of varying jet multiplicity and parton showers. Double counting is avoided by means of a modified truncated shower scheme. This method preserves both the fixed-order accuracy of the parton-level result and the logarithmic accuracy of the parton shower. We discuss the renormalisation and factorisation scale dependence of the approach and present results from an automated implementation in the SHERPA event generator using the test case of W -boson production at the Large Hadron Collider. We observe a dramatic reduction of theoretical uncertainties compared to existing methods which underlines the predictive power of our novel technique.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/bd2a88d6c8d094531835798a80ecee269a337bd4

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Citations in the corpus

NLO QCD+EW predictions for V + jets including off-shell vector-boson decays and multijet merging (2015, methodology): “Indeed, the power counting of [55, 56] shows that inclusive MEPS predictions involve uncancelled logarithms of the generic form”
Mass effects in the Higgs-gluon coupling: boosted vs. off-shell production (2014, methodology): “Our approach generalizes the Meps@Nlo method [87, 88], now including next-to-leading order corrections in the low-energy approximation as well as the top mass dependence at leading order for all jet multiplicities considered.”
Search for electroweak production of supersymmetric particles in final states with two or three leptons at \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\odd (2018, methodology): “Matrix element calculations were merged with the Sherpa parton shower [43] using the ME+PS@NLO prescription [44].”
Combining higher-order resummation with multiple NLO calculations and parton showers in GENEVA (2012, background): “[28, 29] that this description maintains the higher-order accuracy of the underlying matrix elements in their respective phase space range.”
Robust Independent Validation of Experiment and Theory: Rivet version 3 (2019, methodology): “Rivet has been widely used in the development [2–8], validation [9–16] and tuning [17–19] of event generators for Standard Model processes, as well as in the study of parton density functions (PDFs) [20,21].”
Search for additional heavy neutral Higgs and gauge bosons in the ditau final state produced in 36 fb−1 of pp collisions at s=13$$ \sqrt{s}=13 $$ TeV with the ATLAS detector (2018, methodology): “with the Sherpa parton shower [102] using the ME+PS@NLO prescription [103].”
Merging H/W/Z + 0 and 1 jet at NLO with no merging scale: a path to parton shower + NNLO matching (2012, positive): “butions accurate at the NLO level, 3 S , and, at the same time, distributions involving the Higgs boson plus one jet accurate at order 4 S . Several collaborations have addressed this merging problem [6, 7, 8, 9, 10, 11, 12, 13]. They all typically separate the output of each component simulation (t”
Event generation with Sherpa 2.2 (2019, methodology): “nts the MC@NLO method [22, 23]. For NNLO QCD calculations the UN2 LO P S method [24, 25] is used. The merging of multi-jet production processes at leading order [26, 27, 28] and next-to-leading order [29, 30] is based on truncated parton showers. Multiple parton interactions are implemented via the ”
Search for dark matter and other new phenomena in events with an energetic jet and large missing transverse momentum using the ATLAS detector (2017, methodology): “Matrix elements (ME) are calculated for up to two partons at NLO and four partons at LO using OpenLoops [57] and Comix [58], and merged with the Sherpa parton shower (PS) [59] using the ME+PS@NLO prescription [60].”