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A unitarity compatible approach to one-loop amplitudes with massive fermions

  • Simon BadgerEmail author
  • Christian Brønnum-Hansen
  • Francesco Buciuni
  • Donal O’Connell
Open Access
Regular Article - Theoretical Physics

Abstract

We explain how one-loop amplitudes with massive fermions can be computed using only on-shell information. We first use the spinor-helicity formalism in six dimensions to perform generalised unitarity cuts in d dimensions. We then show that divergent wave-function cuts can be avoided, and the remaining ambiguities in the renormalised amplitudes can be fixed, by matching to universal infrared poles in 4 − 2ϵ dimensions and ultraviolet poles in 6 − 2ϵ dimensions. In the latter case we construct an effective Lagrangian in six dimensions and reduce the additional constraint to an on-shell tree-level computation.

Keywords

Perturbative QCD Scattering Amplitudes Field Theories in Higher Dimensions Effective Field Theories 

Notes

Open Access

This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.

Supplementary material

13130_2017_6268_MOESM1_ESM.tgz (20 kb)
ESM 1 (TGZ 19 kb)

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Copyright information

© The Author(s) 2017

Authors and Affiliations

  • Simon Badger
    • 1
    Email author
  • Christian Brønnum-Hansen
    • 2
  • Francesco Buciuni
    • 1
  • Donal O’Connell
    • 2
  1. 1.Institute for Particle Physics Phenomenology, Ogden Centre for Fundamental Physics, Department of PhysicsUniversity of DurhamDurhamU.K.
  2. 2.Higgs Centre for Theoretical Physics, School of Physics and AstronomyThe University of EdinburghEdinburghU.K.

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