Spinning Mellin amplitudes

Abstract

We propose a definition of Mellin amplitudes for conformal correlators involving arbitrary spinning operators in tensor representations of the Lorentz group. These representations cover all bosonic local operators. Our strategy is to perform discrete Mellin transforms on all scalar products involving polarization vectors, so that each polarization vector can be interpreted as the position of a fictitious scalar operator. We establish the general pole structures and factorization properties of these spinning Mellin amplitudes. We also provide a systematic algorithm to derive factorization formulas with arbitrary spinning exchanges, yielding new explicit results up to spin-4. To illustrate the practicality of our formalism, we bootstrap the 3- and 4-point current correlators in a 4d $\mathcal{N}=2$ superconformal field theory, which are dual to gluon scattering amplitudes in $\mathrm{AdS}_5 \times \mathrm{S}^3$. The results agree with the snowflake channel of 6- and 8-point scalar supergluon amplitudes in the literature.