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Related papers: Matrix Elements and Parton Showers in Hadronic Int…

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We extend earlier schemes for merging tree-level matrix elements with parton showers to include also merging with one-loop matrix elements. In this paper we make a first study on how to include one-loop corrections, not only for events with…

High Energy Physics - Phenomenology · Physics 2009-02-02 Nils Lavesson , Leif Lonnblad

We specify recursive equations that could be used to generate a lowest order parton shower for hard scattering in hadron-hadron collisions. The formalism is based on the factorization soft and collinear interactions from relatively harder…

High Energy Physics - Phenomenology · Physics 2009-04-22 Zoltan Nagy , Davison E. Soper

Programs that calculate observables in quantum chromodynamics at next-to-leading order typically suffer from the problem that, when considered as event generators, the events generated consist of partons rather than hadrons and just a few…

High Energy Physics - Phenomenology · Physics 2009-04-13 Michael Kramer , Davison E. Soper

Events containing hadronically decaying heavy particles with large momentum, leading to so-called merged jets, are expected to play a significant role in both searches for new physics and measurements of Standard Model processes at the CERN…

High Energy Physics - Experiment · Physics 2011-09-06 Andrew Altheimer , Gustaaf Brooijmans

We present an overview of recent efforts to calculate the interactions among hadrons using lattice QCD. After outlining the techniques that are used to extract scattering parameters, we detail the latest calculations of meson-meson…

High Energy Physics - Lattice · Physics 2008-12-18 Silas R. Beane , Kostas Orginos , Martin J. Savage

A modified version of the CKKW matrix element merging algorithm is presented, suitable for use in an angular-ordered parton shower, using truncated showers and forced splittings. The algorithm is implemented in the Herwig++ Monte Carlo…

High Energy Physics - Phenomenology · Physics 2009-11-13 Keith Hamilton , Peter Richardson , Jon Tully

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 present an implementation of a parton shower algorithm for hadron colliders and electron-positron colliders based on the dipole factorisation formulae. The algorithm treats initial-state partons on equal footing with final-state partons.…

High Energy Physics - Phenomenology · Physics 2008-11-26 Michael Dinsdale , Marko Ternick , Stefan Weinzierl

We study the matching of multijet matrix elements and shower evolution in the case of top production in hadronic collisions at the Tevatron and at the LHC. We present the results of the matching algorithm implemented in the ALPGEN Monte…

High Energy Physics - Phenomenology · Physics 2010-10-27 Michelangelo L. Mangano , Mauro Moretti , Fulvio Piccinini , Michele Treccani

Understanding hadronic interactions at high energies represents a very important ingredient for modeling high energy cosmic ray air showers. In this paper, we present a new approach to simulate hadronic interactions, including…

High Energy Physics - Phenomenology · Physics 2007-05-23 H. J. Drescher , M. Hladik , S. Ostapchenko , K. Werner

In the algorithm presented here, the ME+PS approach to merge samples of tree-level matrix elements into inclusive event samples is combined with the POWHEG method, which includes exact next-to-leading order matrix elements in the parton…

High Energy Physics - Phenomenology · Physics 2011-09-28 Frank Siegert , Stefan Hoeche , Frank Krauss , Marek Schonherr

We make a thorough comparison between different schemes of merging fixed-order tree-level matrix element generators with parton-shower models. We use the most basic benchmark of the O(alpha_S) correction to e+e- -> jets, where the simple…

High Energy Physics - Phenomenology · Physics 2009-04-30 Nils Lavesson , Leif Lonnblad

The aim of this work is to describe in detail the POWHEG method, first suggested by one of the authors, for interfacing parton-shower generators with NLO QCD computations. We describe the method in its full generality, and then specify its…

High Energy Physics - Phenomenology · Physics 2009-11-13 Stefano Frixione , Paolo Nason , Carlo Oleari

We present an algorithm to combine multiple matrix elements at LO and NLO with a parton shower. We build on the unitarized merging paradigm. The inclusion of higher orders and multiplicities reduce the scale uncertainties for observables…

High Energy Physics - Phenomenology · Physics 2018-04-18 Johannes Bellm , Stefan Gieseke , Simon Plätzer

We summarize recent developments in the VINCIA parton shower. After a brief review of the basics of the formalism, the extension of VINCIA to hadron collisions is sketched. We then turn to improvements of the efficiency of tree-level…

We present a calculation of jet activity associated with pair production of top quarks at hadron colliders and supercolliders. Our approach is based upon a merger of $2\rightarrow 3$ matrix elements with initial and final state parton…

High Energy Physics - Phenomenology · Physics 2009-10-22 H. Baer , C. H. Chen , M. H. Reno

We present a study of effects of QCD radiation in the production of heavy colored states, employing inclusive multi-jet samples obtained by matching matrix elements and parton showers. We discuss several examples showing that matched…

High Energy Physics - Phenomenology · Physics 2009-06-09 Johan Alwall , Simon de Visscher , Fabio Maltoni

The merging procedure of tree-level matrix elements and the subsequent parton shower as implemented in the new event generator SHERPA will be validated for the example of W/Z+jets production at the Tevatron. Comparisons with results…

High Energy Physics - Phenomenology · Physics 2011-03-23 Frank Krauss , Andreas Schaelicke , Steffen Schumann , Gerhard Soff

Jet emission at hadron colliders follows simple scaling patterns. Based on perturbative QCD we derive Poisson and staircase scaling for final state as well as initial state radiation. Parton density effects enhance staircase scaling at low…

High Energy Physics - Phenomenology · Physics 2015-06-11 Erik Gerwick , Tilman Plehn , Steffen Schumann , Peter Schichtel