Adiabatic ekpyrosis: Scale-invariant curvature perturbations from a single scalar field in a contracting universe

Justin Khoury, Paul J. Steinhardt

Research output: Contribution to journalArticle

42 Scopus citations

Abstract

The Universe can be made flat and smooth by undergoing a phase of ultraslow (ekpyrotic) contraction, a condition achievable with a single, canonical scalar field and conventional general relativity. It has been argued, though, that generating scale-invariant density perturbations requires at least two scalar fields and a two-step process that first produces entropy fluctuations and then converts them to curvature perturbations. In this Letter we identify a loophole in the argument and introduce an ekpyrotic model based on a single, canonical scalar field that generates nearly scale-invariant curvature fluctuations through a purely "adiabatic mechanism" in which the background evolution is a dynamical attractor. The resulting spectrum can be slightly red with distinctive non-Gaussian fluctuations.

Original languageEnglish (US)
Article number091301
JournalPhysical review letters
Volume104
Issue number9
DOIs
StatePublished - Mar 5 2010

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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