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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 consider $ZZ$ production in hadronic collisions and present state-of-the-art predictions in QCD perturbation theory matched to parton showers. Next-to-next-to-leading order corrections to the quark-initiated channel are combined with…

High Energy Physics - Phenomenology · Physics 2022-02-02 Luca Buonocore , Gabriël Koole , Daniele Lombardi , Luca Rottoli , Marius Wiesemann , Giulia Zanderighi

We review the methods developed for combining the parton shower approximation to QCD with fixed-order perturbation theory, in such a way as to achieve next-to-leading-order (NLO) accuracy for inclusive observables. This has made it possible…

High Energy Physics - Phenomenology · Physics 2015-06-04 Paolo Nason , Bryan Webber

In this publication, an algorithm is presented that combines the ME+PS approach to merge sequences of tree-level matrix elements into inclusive event samples with the POWHEG method, which combines exact next-to-leading order matrix element…

High Energy Physics - Phenomenology · Physics 2011-08-31 Stefan Hoeche , Frank Krauss , Marek Schonherr , Frank Siegert

We propose a method for matching the next-to-leading order (NLO) calculation of a given QCD process with a parton shower Monte Carlo (MC) simulation. The method has the following features: fully exclusive events are generated, with…

High Energy Physics - Phenomenology · Physics 2010-11-11 S. Frixione , B. R. Webber

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 present results for the QCD production of Z/{\gamma} + 2 jets matched with parton showers using the POWHEG method. Some technicalities relevant for the merging of NLO corrections for this process with parton showers are discussed, and…

High Energy Physics - Phenomenology · Physics 2015-06-04 Emanuele Re

In recent times the algorithms for the simulation of hadronic collisions have been subject to two substantial improvements: the inclusion, within parton showering, of exact higher order tree level matrix elements (MEPS) and, separately,…

High Energy Physics - Phenomenology · Physics 2015-03-14 Keith Hamilton , Paolo Nason

We present novel predictions for the production of $W^+W^-$ pairs in hadron collisions that are next-to-next-to-leading order accurate and consistently matched to a parton shower (NNLOPS). All diagrams that lead to the process $pp\to e^-…

High Energy Physics - Phenomenology · Physics 2019-01-30 Emanuele Re , Marius Wiesemann , Giulia Zanderighi

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.…

High Energy Physics - Phenomenology · Physics 2015-06-05 Stefan Hoeche , Frank Krauss , Marek Schonherr , Frank Siegert

We present the implementation of a new interface in VBFNLO 3.0 supporting all di-boson and tri-boson processes with fully leptonic final states, enabling NLO+PS matched calculations. To demonstrate its capabilities, we study parton shower…

High Energy Physics - Phenomenology · Physics 2024-12-10 Ivan Rosario , Francisco Campanario , Simon Plätzer

We describe how a simulation of Higgs boson production accurate at next-to-next-to-leading order and matched to a parton shower can be built by combining the POWHEG and MiNLO methods and using HNNLO results as input.

High Energy Physics - Phenomenology · Physics 2022-03-02 Emanuele Re

We discuss extensions the CKKW-L and UMEPS tree-level matrix element and parton shower merging approaches to next-to-leading order accuracy. The generalisation of CKKW-L is based on the NL3 scheme previously developed for e+e-…

High Energy Physics - Phenomenology · Physics 2015-06-12 Leif Lonnblad , Stefan Prestel

We present the first NLO QCD+EW predictions for Higgs boson production in association with a l nu or l+ l- pair plus zero or one jets at the LHC. Fixed-order NLO QCD+EW calculations are combined with a QCD+QED parton shower using the…

High Energy Physics - Phenomenology · Physics 2017-09-20 Federico Granata , Jonas M. Lindert , Carlo Oleari , Stefano Pozzorini

Parton showers are among the most widely used tools in collider physics. Despite their key importance, none so far has been able to demonstrate accuracy beyond a basic level known as leading logarithmic (LL) order, with ensuing limitations…

High Energy Physics - Phenomenology · Physics 2020-08-05 Mrinal Dasgupta , Frédéric A. Dreyer , Keith Hamilton , Pier Francesco Monni , Gavin P. Salam , Gregory Soyez

We report on the implementation of an interface between the SANC generator framework for Drell-Yan hard processes, which includes next-to-leading order electroweak (NLO EW) corrections, and the Herwig++ and Pythia8 QCD parton shower Monte…

High Energy Physics - Phenomenology · Physics 2015-05-20 P. Richardson , R. R. Sadykov , A. A. Sapronov , M. H. Seymour , P. Z. Skands

We formulate a collinear partonic shower algorithm that achieves next-to-single-logarithmic (NSL, $\alpha_s^n L^{n-1}$) accuracy for collinear-sensitive non-singlet fragmentation observables. This entails the development of an algorithm for…

High Energy Physics - Phenomenology · Physics 2024-09-16 Melissa van Beekveld , Mrinal Dasgupta , Basem Kamal El-Menoufi , Jack Helliwell , Pier Francesco Monni , Gavin P. Salam

We present a next-to-next-to-leading order accurate description of associated HW production consistently matched to a parton shower. The method is based on reweighting events obtained with the HW plus one jet NLO accurate calculation…

High Energy Physics - Phenomenology · Physics 2016-07-20 William Astill , Wojciech Bizon , Emanuele Re , Giulia Zanderighi

We present a phenomenological study of the current status of the application of our approach of {\it exact} amplitude-based resummation in quantum field theory to precision QCD calculations, by realistic MC event generator methods, as…

High Energy Physics - Phenomenology · Physics 2014-09-22 S. K. Majhi , A. Mukhopadhyay , B. F. L. Ward , S. A. Yost