Bridging dS/CFT and celestial holography via Ward-Takahashi identities

A bstract In [ JHEP 12 (2025) 126 ], we proposed a cosmological-celestial dictionary for a massless scalar field, based on an explicit correspondence between celestial operators and extrapolated cosmological operators in de Sitter spacetime. This operator correspondence provides a link between celestial amplitudes and cosmological correlators. We extend the construction to fields with spin 1 and 2, and find that massless spin fields map to spin fields with continuous mass spectra. In this construction, we identify the de Sitter counterparts of the Nambu-Goldstone modes associated with the asymptotic symmetries in Minkowski spacetime. For U (1) gauge theories, the counterpart is restricted to the massless sector within the continuous Proca spectrum, while for linearized gravity supertranslations are encoded in the partially massless sector and superrotations in the strictly massless sector. Using the identification, we reveal that the associated Ward-Takahashi identities of the cosmological correlators reproduce the conformally soft photon and graviton theorems via the cosmological-celestial dictionary. In particular, the celestial stress tensor is derived from the asymptotic limit of gravitons in de Sitter spacetime.