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

Badger, Simon and Brønnum-Hansen, Christian and Buciuni, Francesco and O’Connell, Donal (2017) 'A unitarity compatible approach to one-loop amplitudes with massive fermions.', Journal of high energy physics., 2017 (6). p. 141.


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.

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Publisher statement: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.
Date accepted:20 June 2017
Date deposited:25 July 2017
Date of first online publication:27 June 2017
Date first made open access:No date available

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