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arXiv · 1703.05734

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

Simon Badger·Christian Brønnum-Hansen·Francesco Buciuni·Donal O'Connell
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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 wavefunction 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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Simon Badger, Christian Brønnum-Hansen, Francesco Buciuni, Donal O'Connell. 2017-03-23. A unitarity compatible approach to one-loop amplitudes with massive fermions. https://doi.org/10.1007/jhep06(2017)141

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