Feeling de Sitter

Abstract

We address the following question: To what extent can a quantum field tell if it has been placed in de Sitter space? Our approach is to use the techniques of non-equilibrium quantum field theory to compute the time evolution of a state which starts off in flat space for (conformal) times $\eta <{\eta }_0$, and then evolves in a de Sitter background turned on instantaneously at $\eta ={\eta }_0$. We find that the answer depends on what quantities one examines. We study a range of them, all based on two-point correlation functions, and analyze which ones approach the standard Bunch-Davies values over time. The outcome of this analysis suggests that the nature of the equilibration process in this system is similar to that in more familiar systems.

25 pages, 11 figures. V2: Final version accepted for publication in PRD. Changes: References added and minor clarifications to the presentation

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• Planck 2013 results. XV. CMB power spectra and likelihood
• Can the universe afford inflation?
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Cited by in corpus (4)

• Quantum correlations for the metric
• Quantum gravity corrections to the conformally coupled scalar self-mass-squared on de Sitter II: kinetic-conformal cross terms
• Cosmic fluctuations from quantum effective action
• Can observations look back to the beginning of inflation?