Large NLO corrections in tt¯ W± and tt¯ tt¯ hadroproduction from supposedly subleading EW contributions

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Abstract

We calculate the complete-NLO predictions for tt¯ W± and tt¯ tt¯ production in proton-proton collisions at 13 and 100 TeV. All the non-vanishing contributions of O(αsiαj) with i + j = 3, 4 for tt¯ W± and i + j = 4, 5 for tt¯ tt¯ are evaluated without any approximation. For tt¯ W± we find that, due to the presence of tW → tW scattering, at 13(100) TeV the O(αsα3) contribution is about 12(70)% of the LO, i.e., it is larger than the so-called NLO EW corrections (the O(αs2α2) terms) and has opposite sign. In the case of tt¯ tt¯ production, large contributions from electroweak tt → tt scattering are already present at LO in the O(αs3α) and O(αs2α2) terms. For the same reason we find that both NLO terms of O(αs4α), i.e., the NLO EW corrections, and O(αs3α2) are large (±15% of the LO) and their relative contributions strongly depend on the values of the renormalisation and factorisation scales. However, large accidental cancellations are present (away from the threshold region) between these two contributions. Moreover, the NLO corrections strongly depend on the kinematics and are particularly large at the threshold, where even the relative contribution from O(αs2α3) terms amounts to tens of percents.

Details

Authors
External organisations
  • Technical University of Munich
  • National Institute for Subatomic Physics
  • Paris-Sorbonne University
  • The French National Centre for Scientific Research (CNRS)
  • Laboratoire de Physique Théorique et Hautes Énergies (LPTHE)
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Subatomic Physics

Keywords

  • NLO Computations, QCD Phenomenology
Original languageEnglish
Article number31
JournalJournal of High Energy Physics
Volume2018
Issue number2
Publication statusPublished - 2018 Feb
Publication categoryResearch
Peer-reviewedYes
Externally publishedYes