The web of gravity amplitudes

Project title: The web of gravity amplitudes
Main applicant: Marco Chiodaroli, Division of Theoretical Physics
Grant amount: SEK 4 150 000 for the period 2025-2028

Scattering amplitudes are quantities that encode fundamental information on how particles interact in a scattering event. Aside from its connection with collider physics, the study of amplitudes has led to novel theoretical developments. Recent work has shown that amplitudes in gravitational theories can be expressed in terms of simpler building blocks, thanks to a method known as the double copy, and has revealed a web of connections between theories that were previously thought to be unrelated. While these developments hint at the existence of a simpler description of gravity, the question remains on whether they can be applied to more realistic physical theories.

This project will create new amplitude methods to investigate broad classes of effective field theories used to describe diverse gravitational processes. These include gravitational-wave emission from compact binaries and the expansion of the universe shortly after the Big Bang. A fundamental part of the project is the generalization of the double copy to de Sitter space, which approximates our universe during inflation.

Results will address the prospect of a simpler description of gravity, which would be paradigm-shifting, and create a common language for tackling important problems in gravitational physics. The project will draw from methods developed in my previous work and from collaboration with three participating researchers, each contributing to one of the work packages.