QCD coherence and the top quark asymmetry

Peter Skands, Bryan Webber, Jan Winter

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42 Citations (Scopus)


Coherent QCD radiation in the hadroproduction of top quark pairs leads to a forward-backward asymmetry that grows more negative with increasing transverse momentum of the pair. This feature is present in Monte Carlo event generators with coherent parton showering, even though the production process is treated at leading order and has no intrinsic asymmetry before showering. In addition, depending on the treatment of recoils, showering can produce a positive contribution to the inclusive asymmetry. We explain the origin of these features, compare them in fixed-order calculations and the Herwig++, Pythia and Sherpa event generators, and discuss their implications.

Original languageEnglish
Article number151
JournalJournal of High Energy Physics
Issue number7
Publication statusPublished - 2012
Externally publishedYes


  • Hadronic colliders
  • QCD phenomenology

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