1. Cutting cosmological correlators
- Author
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Enrico Pajer, Sadra Jazayeri, Mang Hei Gordon Lee, Harry Goodhew, Apollo - University of Cambridge Repository, Apollo-University Of Cambridge Repository, Institut d'Astrophysique de Paris (IAP), and Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
- Subjects
High Energy Physics - Theory ,cosmological model ,optical theorem ,quantum cosmology ,spin ,01 natural sciences ,General Relativity and Quantum Cosmology ,de Sitter ,De Sitter universe ,Friedmann–Lemaître–Robertson–Walker metric ,Cosmological perturbation theory ,correlation function ,media_common ,Physics ,[PHYS.HTHE]Physics [physics]/High Energy Physics - Theory [hep-th] ,Propagator ,graviton ,symbols ,propagator ,resonance: oscillation ,Astrophysics - Cosmology and Nongalactic Astrophysics ,Cosmology and Nongalactic Astrophysics (astro-ph.CO) ,media_common.quotation_subject ,FOS: Physical sciences ,General Relativity and Quantum Cosmology (gr-qc) ,space-time: Robertson-Walker ,quantum mechanics: wave function ,dispersion relation: linear ,Theoretical physics ,symbols.namesake ,Quantum cosmology ,0103 physical sciences ,conservation law ,unitarity ,tree approximation ,inflation ,010306 general physics ,perturbation theory ,Inflation (cosmology) ,010308 nuclear & particles physics ,paper ,monodromy ,inflation: slow-roll approximation ,Graviton ,Astronomy and Astrophysics ,boundary condition ,Universe ,High Energy Physics - Theory (hep-th) ,gravitation ,axion ,cosmological perturbation theory ,n-point function: 5 - Abstract
The initial conditions of our universe appear to us in the form of a classical probability distribution that we probe with cosmological observations. In the current leading paradigm, this probability distribution arises from a quantum mechanical wavefunction of the universe. Here we ask what the imprint of quantum mechanics is on the late time observables. We show that the requirement of unitary time evolution, colloquially the conservation of probabilities, fixes the analytic structure of the wavefunction and of all the cosmological correlators it encodes. In particular, we derive in perturbation theory an infinite set of single-cut rules that generalize the Cosmological Optical Theorem and relate a certain discontinuity of any tree-level $n$-point function to that of lower-point functions. Our rules are closely related to, but distinct from the recently derived Cosmological Cutting Rules. They follow from the choice of the Bunch-Davies vacuum and a simple property of the (bulk-to-bulk) propagator and are astoundingly general: we prove that they are valid for fields with a linear dispersion relation and any mass, any integer spin and arbitrary local interactions with any number of derivatives. They also apply to general FLRW spacetimes admitting a Bunch-Davies vacuum, including de Sitter, slow-roll inflation, power-law cosmologies and even resonant oscillations in axion monodromy. We verify the single-cut rules in a number of non-trivial examples, including four massless scalars exchanging a massive scalar, as relevant for cosmological collider physics, four gravitons exchanging a graviton, and a scalar five-point function., 36 + 18 pages, 4 figures
- Published
- 2021