The inflationary wavefunction from analyticity and factorization
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 n-point functions and for fields of arbitrary mass. Using the cutting rules and dispersion formulas, we are able to compute n-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.
- Publication:
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Journal of Cosmology and Astroparticle Physics
- Pub Date:
- December 2021
- DOI:
- 10.1088/1475-7516/2021/12/018
- arXiv:
- arXiv:2107.10266
- Bibcode:
- 2021JCAP...12..018M
- Keywords:
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- inflation;
- non-gaussianity;
- quantum field theory on curved space;
- string theory and cosmology;
- High Energy Physics - Theory;
- Astrophysics - Cosmology and Nongalactic Astrophysics;
- General Relativity and Quantum Cosmology;
- High Energy Physics - Phenomenology
- E-Print:
- 29 pages + appendices, v2: Typos corrected and references added v3: Added comments on Regge limit in the conclusion