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We here present an extension of the CKKW-L multi-jet merging technique to so-called sector showers as implemented in the Vincia antenna shower. The bijective nature of sector showers allows for efficient multi-jet merging at high…

High Energy Physics - Phenomenology · Physics 2021-05-03 Helen Brooks , Christian T Preuss

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 MCatNLO and POWHEG methods; (b) positive-weight…

High Energy Physics - Phenomenology · Physics 2022-02-02 Paolo Nason , Gavin P. Salam

We present a new approach to combine multiple NLO parton-level calculations matched to parton showers into a single inclusive event sample. The method provides a description of hard multi-jet configurations at next-to leading order in the…

High Energy Physics - Phenomenology · Physics 2013-02-14 Thomas Gehrmann , Stefan Hoeche , Frank Krauss , Marek Schonherr , Frank Siegert

We extend the lowest-order matching of tree-level matrix elements with parton showers to give a complete description at the next higher perturbative accuracy in alpha_s at both small and large jet resolutions, which has not been achieved so…

Higher order calculations are necessary to predict and describe measurements in high energy collider physics. In recent years multiple approaches to combine multiple next-to-leading (NLO) order corrections with parton showers had been…

High Energy Physics - Phenomenology · Physics 2016-07-08 Johannes Bellm

We present a novel method to combine QCD calculations at next-to-next-to-leading order (NNLO) with parton shower (PS) simulations, that can be applied to the production of heavy systems in hadronic collisions, such as colour singlets or a…

High Energy Physics - Phenomenology · Physics 2022-01-11 Pier Francesco Monni , Paolo Nason , Emanuele Re , Marius Wiesemann , Giulia Zanderighi

We give a prescription for attaching parton showers to next-to-leading order (NLO) partonic jet cross sections in electron-positron annihilation. Our method effectively extends to NLO the scheme of Catani, Krauss, Kuhn, and Webber for…

High Energy Physics - Phenomenology · Physics 2007-05-23 Zoltan Nagy , Davison E. Soper

We present a general method to match fully differential next-to-next-to-leading (NNLO) calculations to parton shower programs. We discuss in detail the perturbative accuracy criteria a complete NNLO+PS matching has to satisfy. Our method is…

High Energy Physics - Phenomenology · Physics 2015-06-17 Simone Alioli , Christian W. Bauer , Calvin Berggren , Frank J. Tackmann , Jonathan R. Walsh , Saba Zuberi

We present predictions for $W^+W^-$ production (with exact decays) that are next-to-next-to-leading order (NNLO) accurate and consistently matched to a parton shower. The matching is achieved by upgrading, with MiNLO, the NLO calculation of…

High Energy Physics - Phenomenology · Physics 2018-08-29 Emanuele Re

A new method to construct event-generators based on next-to-leading order QCD matrix-elements and leading-logarithmic parton showers is proposed. Matrix elements of loop diagrams as well as those of a tree level can be generated using an…

High Energy Physics - Phenomenology · Physics 2007-05-23 Y. Kurihara

In this publication, uncertainties in and differences between the MC@NLO and POWHEG methods for matching next-to-leading order QCD calculations with parton showers are discussed. Implementations of both algorithms within the event generator…

High Energy Physics - Phenomenology · Physics 2012-09-25 Stefan Hoeche , Frank Krauss , Marek Schonherr , Frank Siegert

The next-to-leading order (NLO) corrections to Drell-Yan slepton pair production are merged with parton shower evolution via the POWHEG method in Herwig++. The NLO corrections at the level of event generation alter the shape of observables…

High Energy Physics - Phenomenology · Physics 2012-08-02 Ilan Fridman-Rojas , Peter Richardson

We have implemented a systematic procedure for combining parton shower algorithms with next-to-leading order QCD calculations for the case of jet production in deep-inelastic electron-proton scattering. Using this method we have computed…

High Energy Physics - Phenomenology · Physics 2009-11-07 B. Pötter , T. Schörner

We introduce an improvement to the FxFx matrix element merging procedure for $pp\to t \bar t W$ production at NLO in QCD with one and/or two additional jets. The main modification is an improved treatment of jets that are not…

High Energy Physics - Phenomenology · Physics 2021-11-24 Rikkert Frederix , Ioannis Tsinikos

We compare a NLO W gamma matrix element generator with the leading order calculation in Pythia . A matching scheme between a next-to-leading order W gamma matrix element generator by Baur et. al. and the Pythia parton shower is presented.…

High Energy Physics - Phenomenology · Physics 2010-02-24 D. Majumder , K. Mazumdar , T. Sjostrand

We report on a method for matching the next-to-leading order calculation of QCD jet production in e+e- annihilation with a Monte Carlo parton shower event generator (MC) to produce realistic final states. The final result is accurate to…

High Energy Physics - Phenomenology · Physics 2008-11-26 Michael Krämer , Stephen Mrenna , Davison E. Soper

We derive an improved prescription for the merging of matrix elements with parton showers, extending the CKKW approach. A flavour-dependent phase space separation criterion is proposed. We show that this new method preserves the logarithmic…

High Energy Physics - Phenomenology · Physics 2010-03-05 Stefan Hoeche , Frank Krauss , Steffen Schumann , Frank Siegert

We propose a scheme that could offer a convenient Monte Carlo sampling of next-to-leading-order matrix elements and, at the same time, allow the interfacing of such parton configurations with a parton-shower approach for the estimation of…

High Energy Physics - Phenomenology · Physics 2007-05-23 Christer Friberg , Torbjörn Sjöstrand

The search for new interactions and particles in high-energy collider physics relies on precise background predictions. This has led to many advances in combining precise fixed-order cross-section calculations with detailed event generator…

High Energy Physics - Phenomenology · Physics 2021-11-24 Stefan Prestel

To prepare for the next generation particle collider, likely to be a high-energy precision-frontier electron-positron machine, theoretical predictions must improve in tandem. One aspect in which it is necessary to build on the progress made…

High Energy Physics - Phenomenology · Physics 2026-03-09 Lois Flower , Marek Schönherr