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.

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

Badger S.;
2017

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.
JOURNAL OF HIGH ENERGY PHYSICS
2017
6
N/A
N/A
http://arxiv.org/abs/1703.05734v2
Effective Field Theories; Field Theories in Higher Dimensions; Perturbative QCD; Scattering Amplitudes; High Energy Physics - Phenomenology; High Energy Physics - Phenomenology; High Energy Physics - Theory
Badger S.; Bronnum-Hansen C.; Buciuni F.; O'Connell D.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2318/1770898
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