Twistor theory and scattering amplitudes on strong curved backgrounds

Thesis

We apply twistor theory to a variety of problems in quantum field theory in the presence of strong backgrounds, i.e. field configurations solving the classical equations of motions that are treated non-perturbatively. We give all-multiplicity formulae for any tree-level, colour-ordered MHV form factor around self-dual radiative gauge fields. We construct Killing spinors around a self-dual dyon background and use them to construct plane wavelike linear fields of arbitrary helicity propagating on the background. The twistor description of these fields allows to derive a compact formula for the tree-level, colour-ordered gluon MHV amplitude at all multiplicity. In the spirit of the (classical) double-copy, we use these results and a novel twistor sigma model to construct the n-point tree-level graviton MHV amplitude on the self-dual Taub-NUT space-time. As an application, we show that these amplitudes imply that the celestial chiral algebras are undeformed by the backgrounds, both in the gauge theory and gravitational sectors. We conclude by giving a twistorial derivation of the celestial chiral algebra on AdS4 and propose an extension of this algebra around the unique self-dual metric in the AdS-Taub-NUT family.

Authors: Bogna, G

• DOI: 10.5287/ora-qm4xneqoo
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English