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Profile picture of Leif Lönnblad. Photo.

Leif Lönnblad

Professor of Theoretical Physics

Profile picture of Leif Lönnblad. Photo.

Merging parton showers and matrix elements -- back to basics

Author

  • Nils Lavesson
  • Leif Lönnblad

Summary, in English

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 kinematics allows us to study in detail the transition between the matrix-element and parton-shower regions. We find that the CKKW-based schemes give a reasonably smooth transition between these regions, although problems may occur if the parton shower used is not ordered in transverse momentum. However, the so-called Pseudo-Shower and MLM schemes turn out to have potentially serious problems due to different scale definitions in different regions of phase space, and due to sensitivity to the details in the initial conditions of the parton shower programs used.

Department/s

  • Theoretical Particle Physics

Publishing year

2008

Language

English

Publication/Series

Journal of High Energy Physics

Volume

4

Issue

85

Document type

Journal article

Publisher

Springer

Topic

  • Subatomic Physics

Keywords

  • Phenomenological Models
  • Jets
  • Parton Model
  • QCD

Status

Published

ISBN/ISSN/Other

  • ISSN: 1029-8479