scholarly journals Controlling inclusive cross sections in parton shower + matrix element merging

2013 ◽  
Vol 2013 (8) ◽  
Author(s):  
Simon Plätzer
Keyword(s):  
Matrix Element ◽  
Cross Sections ◽  
Parton Shower

scholarly journals IR-improved DGLAP parton shower effects for associated production of a W boson and jets in pp collisions at s = 8 and 13 TeV

2020 ◽  
Vol 35 (32) ◽  
pp. 2050197
Author(s):  
B. Shakerin ◽  
B. F. L. Ward
Keyword(s):  
Matrix Element ◽  
Energy Dependence ◽  
Cross Sections ◽  
Parton Shower ◽  
W Boson ◽  
Exact Formula ◽  
Leading Order ◽  
Angular Correlations ◽  
Associated Production ◽  
Theoretical Predictions

In a previous paper, hereafter referred to as I, we have analyzed the 7 TeV LHC data on [Formula: see text] events from the standpoint of IR-improved DGLAP parton shower effects, using the IR-improved Herwiri1.031 parton shower MC in comparison with the Herwig6.5 parton shower MC in the context of the exact [Formula: see text] matrix element matched parton shower framework provided by MG5_aMC@NLO. In this paper, we extend this analysis to the LHC 8 and 13 TeV data to investigate the energy dependence of the results obtained in I. Specifically, [Formula: see text] events are generated in the MADGRAPH5_aMC@NLO framework and showered by HERWIG6.521 and HERWIRI1.031 with [Formula: see text] and 0 GeV, respectively. The differential cross sections are reported as functions of jet multiplicity, transverse linear momenta [Formula: see text], the jet pseudorapidity [Formula: see text] and the scalar sum of jet transverse momenta [Formula: see text] for different jet multiplicities 1–3. The dijet cross sections as functions of transverse linear momenta, invariant mass of the dijet and the jet separation are shown as well. Distributions of angular correlations between the jets and the muon are examined as well and the corresponding cross sections are presented. The respective measured cross sections are compared with the exact next-to-leading-order (NLO) matrix element matched parton shower theoretical predictions provided by MADGRAPH5_aMC@NLO/HERWIRI1.031 [Formula: see text] and MADGRAPH5_aMC@NLO/HERWIG6.521 [Formula: see text] and the phenomenological consequences are discussed with an eye toward their energy dependence.

scholarly journals Production of prompt photons associated with jets at LHC in kT-factorization

2019 ◽  
Vol 222 ◽  
pp. 03015
Author(s):  
Maxim Malyshev ◽  
Artem Lipatov ◽  
Hannes Jung
Keyword(s):  
Monte Carlo ◽  
Cross Sections ◽  
Parton Shower ◽  
Gluon Fusion ◽  
Monte Carlo Generator ◽  
Hadronic Jets ◽  
Factorization Approach ◽  
Associated Production ◽  
Parton Showering ◽  
Collinear Limit

We use the kT–factorization approach to calculate total and differential cross sections of associated production of prompt photons and hadronic jets at the LHC energies. Our consideration relies on the pegasus Monte-Carlo generator with implemented ℴ(αα2s) off-shell gluon–gluon fusion subprocess g*g* → γqq− and several subleading quark-initiated contributions from ℴ(ααs) and ℴ(αα2s) subprocesses, taken into account in the collinear limit. Using Monte-Carlo generators CASCADE and PYTHIA, we investigate parton showering effects and compare our predictions with the data, taken by CMS and ATLAS collaborations at the LHC. We demostrate reasonabledescription of the data and the importance of parton shower effects in the kT–factorization.

scholarly journals An event generator for same-sign W-boson scattering at the LHC including electroweak corrections

2019 ◽  
Vol 79 (9) ◽  
Author(s):  
Mauro Chiesa ◽  
Ansgar Denner ◽  
Jean-Nicolas Lang ◽  
Mathieu Pellen
Keyword(s):  
Monte Carlo ◽  
Matrix Element ◽  
Parton Shower ◽  
W Boson ◽  
Event Generator ◽  
Monte Carlo Program ◽  
The Matrix ◽  
Electroweak Corrections

Abstract In this article we present an event generator based on the Monte Carlo program Powheg in combination with the matrix-element generator Recola. We apply it to compute NLO electroweak corrections to same-sign W-boson scattering, which have been shown to be large at the LHC. The event generator allows for the generation of unweighted events including the effect of the NLO electroweak corrections matched to a QED parton shower and interfaced to a QCD parton shower. In view of the expected experimental precision of future measurements, the use of such a tool will be indispensable.

scholarly journals Hard photon production and matrix-element parton-shower merging

2010 ◽  
Vol 81 (3) ◽  
Author(s):  
Stefan Höche ◽  
Steffen Schumann ◽  
Frank Siegert
Keyword(s):  
Matrix Element ◽  
Parton Shower ◽  
Photon Production ◽  
Hard Photon

GT± STRENGTH DISTRIBUTION IN 48Sc AND 116In MEASURED BY (p, n) AND (n, p) REACTIONS AT 300 MeV AND THEIR IMPLICATIONS FOR 2ν2β DECAY

2009 ◽  
Vol 18 (10) ◽  
pp. 2119-2123
Author(s):  
HIDE SAKAI ◽  
KENTARO YAKO ◽  
ICHOR COLLABORATION
Keyword(s):  
Matrix Element ◽  
Excitation Energy ◽  
Cross Sections ◽  
Nuclear Matrix ◽  
Differential Cross ◽  
Nuclear Matrix Element ◽  
Strength Distribution ◽  
Angular Distributions ◽  
Decomposition Technique ◽  
Gamow Teller

Angular distributions of the double differential cross sections for the 48 Ca , 116 Cd (p, n) and the 48 Ti , 116 Sn (n, p) reactions were measured at 300 MeV. A multipole decomposition technique was applied to the spectra to extract the Gamow-Teller (GT) transition strengths. In both (n, p) spectra beyond 8 MeV excitation energy extra B( GT +) strengths which are not predicted by either shell model or QRPA calculations. This extra B( GT +) strengths certainly contribute to the nuclear matrix element of the 2ν2β-decay.

scholarly journals Multiplicative-accumulative matching of NLO calculations with parton showers

2022 ◽  
Vol 2022 (1) ◽  
Author(s):  
Paolo Nason ◽  
Gavin P. Salam
Keyword(s):  
Phase Space ◽  
Matrix Element ◽  
Parton Shower ◽  
Leading Order ◽  
Positive Weight ◽  
New Approach ◽  
The Matrix ◽  
Core Features

Abstract We propose a new approach for combining next-to-leading order (NLO) and parton shower (PS) calculations so as to obtain three core features: (a) applicability to general showers, as with the MC@NLO and POWHEG methods; (b) positive-weight events, as with the KrkNLO and POWHEG methods; and (c) all showering attributed to the parton shower code, as with the MC@NLO and KrkNLO methods. This is achieved by using multiplicative matching in phase space regions where the shower overestimates the matrix element and accumulative (additive) matching in regions where the shower underestimates the matrix element, an approach that can be viewed as a combination of the MC@NLO and KrkNLO methods.

scholarly journals Reweighting QCD matrix-element and parton-shower calculations

2016 ◽  
Vol 76 (11) ◽  
Author(s):  
Enrico Bothmann ◽  
Marek Schönherr ◽  
Steffen Schumann
Keyword(s):  
Matrix Element ◽  
Parton Shower
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