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

作者:Badger Simon*; Bronnum Hansen Christian; Buciuni Francesco; O'Connell Donal
来源:The Journal of High Energy Physics, 2017, 2017(6): 141.
DOI:10.1007/JHEP06(2017)141

摘要

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 - 2 epsilon dimensions and ultraviolet poles in 6 - 2 epsilon 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.

  • 出版日期2017-6-27