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

Journal of High Energy Physics

Donal O’Connell¹  Christian Brønnum-Hansen¹  Simon Badger²  Francesco Buciuni² 

[1] Higgs Centre for Theoretical Physics, School of Physics and Astronomy, The University of Edinburgh;Institute for Particle Physics Phenomenology, Ogden Centre for Fundamental Physics, Department of Physics, University of Durham;

关键词: Perturbative QCD;    Scattering Amplitudes;    Field Theories in Higher Dimensions;    Effective Field Theories;   

DOI  :  10.1007/JHEP06(2017)141

来源: DOAJ

【 摘 要 】

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.

【 授权许可】

Unknown