Towards a Cosmological Dual to Inflation

Abstract

We derive all single-field cosmologies with unit sound speed that generate scale invariant curvature perturbations on a dynamical attractor background. We identify three distinct phases: slow-roll inflation; a slowly contracting adiabatic ekpyrotic phase, described by a rapidly-varying equation of state; and a novel adiabatic ekpyrotic phase on a slowly expanding background. All of these yield identical power spectra. The degeneracy is broken at the 3-point level: unlike the nearly gaussian spectrum of slow-roll inflation, adiabatic ekpyrosis predicts large non-gaussianities on small scales.

arXiv comment7 pages, 1 figure. v2: Included section reviewing non-gaussianity calculation, added references

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Cited by in corpus (32)

• An Infinite Set of Ward Identities for Adiabatic Modes in Cosmology
• A Galileon Design of Slow Expansion
• DBI Realizations of the Pseudo-Conformal Universe and Galilean Genesis Scenarios
• The Pseudo-Conformal Universe: Scale Invariance from Spontaneous Breaking of Conformal Symmetry
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• Towards degeneracy breaking of early universe models
• The four fixed points of scale invariant single field cosmological models
• Aspects of inflation and the very early universe