paper

The Inflationary Wavefunction from Analyticity and Factorization

arXiv:2107.10266 · doi:10.1088/1475-7516/2021/12/018

Abstract

We study the analytic properties of tree-level wavefunction coefficients in quasi-de Sitter space. We focus on theories which spontaneously break dS boost symmetries and can produce significant non-Gaussianities. The corresponding inflationary correlators are (approximately) scale invariant, but are not invariant under the full conformal group. We derive cutting rules and dispersion formulas for the late-time wavefunction coefficients by using factorization and analyticity properties of the dS bulk-to-bulk propagator. This gives a unitarity method which is valid at tree-level for general -point functions and for fields of arbitrary mass. Using the cutting rules and dispersion formulas, we are able to compute -point functions by gluing together lower-point functions. As an application, we study general four-point, scalar exchange diagrams in the EFT of inflation. We show that exchange diagrams constructed from boost-breaking interactions can be written as a finite sum over residues. Finally, we explain how the dS identities used in this work are related by analytic continuation to analogous identities in Anti-de Sitter space.

29 pages + appendices, v2: Typos corrected and references added v3: Added comments on Regge limit in the conclusion

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