Speaker
Description
Celestial holography aims to recast flat-space physics in terms of conformal data on the celestial sphere. This invites the use of CFT techniques to analyse observables in flat holography. In this talk I will introduce a Mellin-amplitude representation for celestial correlators, inspired by the Mellin amplitudes for holographic correlators in AdS/CFT. Celestial Mellin amplitudes streamline both computation and interpretation of celestial correlators, and exhibit an AdS-like analytic structure: contact interactions give polynomial Mellin amplitudes, while particle exchange appears through a characteristic pattern of poles. After illustrating the method in scalar theories, we extend it to the exchange of spinning fields. For massless external scalars we obtain closed-form celestial Mellin amplitudes for spin-1 and spin-2 exchange (massless and massive) and extract direct-channel OPE data, identifying the contributions of the spin-1 current and the spin-2 stress tensor, together with the boundary gauge boson and graviton.
Based on arXiv:2412.11992 and arXiv:2511.09501.