Theoretical Physics Wednesday Seminar: Paul McFadden

Double copy structure in conformal field theory

Conformal symmetry places strong constraints on the form of correlation functions. In this talk, we review recent developments in conformal field theory (CFT) from the perspective of momentum space, which is natural for many applications including inflationary cosmology as well as for making connections with scattering amplitudes. We show how scattering amplitudes can be extracted from CFT correlators by taking a certain flat space limit, and how the double copy structure of amplitudes is then naturally inherited by CFT correlators. In particular, stress tensor correlators have poles whose residues correspond to gravitational scattering amplitudes, and these residues are a double copy of the analogous residues appearing in current correlators, which correspond to gauge theory amplitudes. The same also holds for mixed correlators featuring marginal scalars. In odd spacetime dimensions these residues are easy to extract, but in even dimensions correlators have branch cuts meaning a specific analytic continuation is required.