Twistorial Foundation for the Classical Double Copy

Abstract

The classical double copy relates exact solutions of gauge, gravity, and other theories. Although widely studied, its origins and domain of applicability have remained mysterious. In this Letter, I show that a particular incarnation - the Weyl double copy - can be derived using well-established ideas from twistor theory. As well as explaining where the Weyl double copy comes from, the twistor formalism also shows that it is more general than previously thought.