Snowmass White Paper: the Double-Copy and its Applications

Authors: Tim Adamo, John Joseph M. Carrasco, Mariana Carrillo-González, Marco Chiodaroli, Henriette Elvang, Henrik Johansson, Donal O'Connell, Radu Roiban, Oliver Schlotterer Preprint number: UUITP-21/22 The double-copy is, in essence, a map between scattering amplitudes in a broad variety of familiar field and string theories. In addition to the mathematically rich intrinsic structure, it underlies a multitude of active research directions and has a range of interesting applications in quantum, classical and effective field theories, including broad topics such as string theory, particle physics, astrophysics, and cosmology. This Snowmass White Paper provides a brief introduction to the double-copy, its applications, current research and future challenges.