Apr 7 – 10, 2019
Imperial College London
Europe/London timezone

Integration-by-parts identities and multi-loop QCD amplitudes

Apr 8, 2019, 3:45 PM
Clore Lecture Theatre, Huxley 213 (Imperial College London)

Clore Lecture Theatre, Huxley 213

Imperial College London

Imperial College London Prince Consort Road South Kensington London


Herschel Chawdhry (University of Cambridge)


As the LHC gathers ever more data and makes measurements with increasingly high precision, it is essential for theorists to match this precision when making predictions for cross-sections. In QCD and other gauge theories, this high precision is achieved by including multi-loop Feynman diagrams when calculating scattering amplitudes. Integration-by-parts identities (IBPs) are widely used when computing the associated multi-loop integrals. The solution of large systems of IBPs is a major bottleneck in the computation of high-precision QCD amplitudes for processes observed at the LHC, such as 3-jet production.
In this talk, I will discuss my work on IBPs, first presented in arXiv:1805.09182, where we introduce a new strategy for solving systems of IBPs, which we believe to be especially applicable to problems with many kinematic scales and/or many master integrals. Using this strategy, we have solved the IBPs needed for the computation of any planar 2-loop 5-point massless amplitude in QCD. We have also derived some new results for the associated non-planar integrals. Ultimately, we expect that the remaining non-planar contributions will be computable in analytic form, which would allow cross-sections for processes such as 3-jet production to be predicted at Next-to-next-to-leading order in QCD, reducing theoretical uncertainties down to a few percent.

Presentation materials