
Open access
Date
2022Type
- Journal Article
Abstract
The Local Unitarity (LU) representation of differential cross-sections locally realises the cancellations of infrared singularities predicted by the Kinoshita-Lee-Nauenberg theorem. In this work we solve the two remaining challenges to enable practical higher-loop computations within the LU formalism. The first concerns the generalisation of the LU representation to graphs with raised propagators. The solution to this problem results in a generalisation of distributional Cutkosky rules. The second concerns the regularisation of ultraviolet and spurious soft singularities, solved using a fully automated and local renormalisation procedure based on Bogoliubov's R-operation. We detail an all-order construction for the hybrid (MS) over bar and On-Shell scheme whose only analytic input is single-scale vacuum diagrams. We validate this novel technology by providing (semi-)inclusive results for two multi-leg processes at NLO, study limits of individual supergraphs up to N3LO and present the first physical NNLO cross-sections computed fully numerically in momentum-space, namely for the processes gamma* -> jj and gamma*-> t (t) over bar. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000578382Publication status
publishedExternal links
Journal / series
Journal of High Energy PhysicsVolume
Pages / Article No.
Publisher
SpringerSubject
Automation; Higher-Order Perturbative Calculations; Renormalization and Regularization; Scattering AmplitudesFunding
694712 - Automatization of perturbative QCD at very high orders (EC)
179016 - Singlular structure of two-loop amplitudes and their numerical evaluation (SNF)
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