Open Collections

He, Fuhai

University of British Columbia

The double-copy relation is the conjecture that amplitudes in any gravitational theory can be obtained by appropriately "squaring" some gauge theory amplitudes. This relation has been proven at tree levels and many examples exist at loop levels. The construction of double copy at high loops can be facilitated by unitarity methods which allow one to build loop amplitudes from trees. We explore the application of the unitarity method in the worldline quantum field theory (WQFT) at next-to-next-to leading order (NNLO), which is analogous to two loop level in traditional quantum field theory. WQFT is a recently developed formalism to compute classical gravitational observables in the post-Minkowskian regime. In WQFT, the extraction of the classical part of gravitational amplitudes is streamlined so one bypasses the need for taking various subtle limits. This thesis introduces the double copy relation and the unitarity method in traditional quantum field theory and explains how they extend to WQFT. We also introduce the method of differential equations for solving Feynman integrals with dimensional regulation.

Text

2024-10-21

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/89466

Physics

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/