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Related papers: Merging parton showers and matrix elements -- back…

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We study contributions from nonperturbative effects and parton showering in NLO event generators, and present applications to jet final states. We find pT-dependent and rapidity-dependent corrections which can affect the shape of observed…

High Energy Physics - Phenomenology · Physics 2013-04-29 S. Dooling , P. Gunnellini , F. Hautmann , H. Jung

When parton distributions are falling steeply as the momentum fractions of the partons increases, there are effects that occur at each order in $\alpha_s$ that combine to affect hard scattering cross sections and need to be summed. We show…

High Energy Physics - Phenomenology · Physics 2016-11-03 Zoltan Nagy , Davison E. Soper

Machine learning methods incorporating deep neural networks have been the subject of recent proposals for new hadronic resonance taggers. These methods require training on a dataset produced by an event generator where the true class labels…

High Energy Physics - Phenomenology · Physics 2017-01-25 James Barnard , Edmund Noel Dawe , Matthew J. Dolan , Nina Rajcic

We present a simple formalism for parton-shower Markov chains. As a first step towards more complete uncertainty bands, we incorporate a comprehensive exploration of the ambiguities inherent in such calculations. To reduce this uncertainty,…

High Energy Physics - Phenomenology · Physics 2008-11-26 Walter T. Giele , David A. Kosower , Peter Z. Skands

We present differential cross sections for the production of top-quark pairs in conjunction with up to two jets, computed at next-to leading order in perturbative QCD and consistently merged with a parton shower in the Sherpa+OpenLoops…

High Energy Physics - Phenomenology · Physics 2015-07-01 Stefan Höche , Frank Krauss , Philipp Maierhoefer , Stefano Pozzorini , Marek Schonherr , Frank Siegert

QCD predictions for final states with multiple jets in hadron collisions make use of multi-jet merging methods, which allow one to combine consistently the contributions from hard scattering matrix elements with different parton…

High Energy Physics - Phenomenology · Physics 2022-08-15 Aron Mees van Kampen

We show how the use of a see-saw mechanism based on a $3 \times 3$ neutrino mass matrix texture can considerably simplify Higgs sectors for quark-lepton symmetric models (and for Standard Model extensions generally). The main theory we…

High Energy Physics - Phenomenology · Physics 2009-10-28 R. Foot , R. R. Volkas

High-quality simulated data is crucial for particle physics discoveries. Therefore, parton shower algorithms are a major building block of the data synthesis in event generator programs. However, the core algorithms used to generate parton…

High Energy Physics - Phenomenology · Physics 2022-11-09 Gösta Gustafson , Stefan Prestel , Michael Spannowsky , Simon Williams

We discuss the necessary steps for implementing an angularly ordered (AO) electroweak (EW) parton shower in Herwig 7 multi-purpose event generator. This includes calculating the helicity-dependent quasi-collinear EW branching functions that…

High Energy Physics - Phenomenology · Physics 2022-04-26 M. R. Masouminia , P. Richardson

We perform a systematic and comprehensive analysis of sub-leading colour corrections in perturbative QCD processes involving multiple soft gluon emissions. This necessitates going beyond the standard parton shower paradigm in order to…

High Energy Physics - Phenomenology · Physics 2025-05-22 Jeffrey R. Forshaw , Simon Plätzer , Fernando Torre González

Modern parton showers are built using one of two models: dipole showers or angular ordered showers. Both have distinct strengths and weaknesses. Dipole showers correctly account for wide-angle, soft gluon emissions and track the leading…

High Energy Physics - Phenomenology · Physics 2020-09-02 Jeffrey R. Forshaw , Jack Holguin , Simon Plätzer

We report on a new formalism for parton showers whose fixed-order expansion can be corrected through next-to-next-to-leading order (NNLO) in QCD. It is the first such formalism we are aware of that has no dependence on any auxiliary scales…

High Energy Physics - Phenomenology · Physics 2023-10-31 Peter Skands , Christian T. Preuss

We present first results from a new parton shower event generator, Deductor. Anticipating a need for an improved treatment of parton color and spin, the structure of the generator is based on the quantum density matrix in color and spin…

High Energy Physics - Phenomenology · Physics 2015-06-18 Zoltan Nagy , Davison E. Soper

The leading-order accurate description of top quark pair production, as usually employed in standard Monte Carlo event generators, gives no rise to the generation of a forward--backward asymmetry. Yet, non-negligible -- differential as well…

High Energy Physics - Phenomenology · Physics 2015-06-15 Jan Winter , Peter Z. Skands , Bryan R. Webber

The Parton-Shower algorithm implement in the Pythia generator is applied multiple times to the same parton-level configuration to estimate the systematic uncertainty affecting large-radius jet substructure variables associated with the…

High Energy Physics - Experiment · Physics 2020-10-09 Riccardo Di Sipio

Spontaneous symmetry breaking is well understood through the classical "Mexican Hat" picture, which describes many quantum phases of matter. Recently, several new classes of quantum phases of matter, such as topological orders and symmetry…

Strongly Correlated Electrons · Physics 2015-05-01 Fangzhou Liu , Xiao-Gang Wen

This paper assesses the uncertainties inherent to parton shower simulations at double logarithmic accuracy, with a focus on their impact on jet quenching studies in high-energy heavy-ion collisions. For that purpose, we developed a massless…

High Energy Physics - Phenomenology · Physics 2025-07-29 Carlota Andres , Liliana Apolinário , Néstor Armesto , André Cordeiro , Fabio Dominguez , José Guilherme Milhano

We reframe common tasks in jet physics in probabilistic terms, including jet reconstruction, Monte Carlo tuning, matrix element - parton shower matching for large jet multiplicity, and efficient event generation of jets in complex,…

High Energy Physics - Phenomenology · Physics 2021-09-08 Kyle Cranmer , Matthew Drnevich , Sebastian Macaluso , Duccio Pappadopulo

We introduce a method for matching the neutral-current deep inelastic scattering process with parton showers at first order in the strong coupling. This multiplicative matching is achieved by reweighting leading-order Born-level events and…

High Energy Physics - Phenomenology · Physics 2026-05-13 Ilkka Helenius , Joni O. Laulainen , Christian T. Preuss