Interleaved parton showers and tuning prospects

By Richard Corke, Torbjörn Sjöstrand. 2010

386 citations recorded by the source corpus.

General-purpose Monte Carlo event generators have become important tools in particle physics, allowing the simulation of exclusive hadronic final states. In this article we examine the Pythia 8 generator, in particular focusing on its parton-shower algorithms. Some relevant new additions to the code are introduced, that should allow for a better description of data. We also implement and compare with 2 → 3 real-emission QCD matrix elements, to check how well the shower algorithm fills the phase space away from the soft and collinear regions. A tuning of the generator to Tevatron data is performed for two PDF sets and the impact of first new LHC data is examined.

Subfields: Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/7a15c1568aaa48db1b62deb26f55dc8d5891e188

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In Nuclear and High Energy Physics

Citations in the corpus

Handbook of LHC Higgs Cross Sections: 3. Higgs Properties (2013, methodology): “As a cross check, the MPI-induced variations in the sele ct d cross sections have been studied (based on stable particles) also in the Pythia 6 DW [272], Pythia 6 Pe rugia 2011 [273] and Pythia 8 4C [274] tunes.”
Measurement of the Z/ѵ* boson transverse momentum distribution in pp collisions at √s = 7 TeV with the ATLAS detector (2014, methodology): “The steerable parameters not used in the tuning are set to the values defined by the tune 4C [35].”
Boosted objects and jet substructure at the LHC. Report of BOOST2012, held at IFIC Valencia, 23rd–27th of July 2012 (2013, methodology): “426), tune 4C [62] with CTEQ6L1 PDF [63] of the newer C++ Pythia8 generator [18] (version 8.”
Tuning PYTHIA 8.1: the Monash 2013 tune (2014, methodology): “Most previous tunes, including the current default Tune 4C [9], have used a Gaussian assumption [76] for the transverse matter distribution, but this appears to give a slightly too low UE level (for a given average MB level).”
Multiplicity dependence of pion, kaon, proton and lambda production in p–Pb collisions at sNN=5.02 TeV (2013, background): “6, which shows the results obtained by applying the same fitting procedure to transverse momentum distributions from the simulation of pp collisions at √ s = 7 TeV with the PYTHIA8 event generator (tune 4C) [61], a model not including any collective system expansion.”
String formation beyond leading colour (2015, background): “175 [29] (tune 4C [56]), with and without colour reconnections switched on.”
Multiplicity dependence of the average transverse momentum in pp, p-Pb, and Pb-Pb collisions at the LHC (2013, methodology): “Although a good description of Tevatron data [26] was achieved within the PYTHIA 8 model [31], which also described the early LHC data [32], full consistency of the data description within models is yet to be achieved [33].”
Search for dark matter and large extra dimensions in monojet events in pp collisions at sqrt(s) = 7 TeV (2012, methodology): “130 [42, 43], using tune 4C [44] and the CTEQ 6.”
Jet energy measurement and its systematic uncertainty in proton–proton collisions at $$\sqrt{s}=7$$s=7 TeV with the ATLAS detector (2015, methodology): “Minimum bias events are generated using Pythia8 [47] with the 4C tune [48] and MRST LO** PDF set.”
Matching tree-level matrix elements with interleaved showers (2011, methodology): “However, this is now achieved through another damping mechanism described in [20], which means that the rapidity ordering is no longer needed to achieve a reasonable description of data.”
Pileup per particle identification (2014, neutral): “5 η pT = [25-50] GeV, |”
Towards an understanding of jet substructure (2013, background): “The top-left plot of figure 16 shows the comparison between the different showers in Pythia 6 and Pythia 8: the virtuality-ordered one in Pythia 6, our default, and the ptordered one in Pythia 6 [70] (in the Perugia 2011 [71] tune) and the pt-ordered shower from Pythia 8 [18] (in the 4C tune [72]).”
Extraction and validation of a new set of CMS pythia8 tunes from underlying-event measurements (2019, background): “The CMS PYTHIA8 tune CUETP8S1-CTEQ6L1 is based instead on the tune 4C [8].”