2002/03/31 by Ruth Durrer, R. Durrer, Filippo Vernizzi +1 · 135 citations
Mathematics · Physics and Astronomy · #Adiabatic process #Anisotropy #Big Bang (financial markets) #Black Holes and Theoretical Physics #Cosmic microwave background #Cosmology #Cosmology and Gravitation Theories #Dark energy #Dilaton #Ekpyrotic universe #Galaxies: Formation, Evolution, Phenomena #Mathematics #Metric expansion of space #Physical cosmology #Physics #Quantum mechanics #Scalar (mathematics) #Scale (ratio) #Scale invariance #Spectral density #Statistical physics #Statistics #Theoretical physics #Ultimate fate of the universe #astro-ph #hep-ph
paper · pdf · open access · doi:10.1103/physrevd.66.083503
published in Physical review. D. Particles, fields, gravitation, and cosmology/Physical review. D. Particles and fields 66(8) (American Physical Society) · 11 pages, 1 figure, revised version with small corrections to match version in print. Results and conclusions unchanged
arxiv created 2002/09/04 · openalex publication_date 2002/10/11 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
At low energy, the four-dimensional effective action of the ekpyrotic model of the universe is equivalent to a slightly modified version of the pre-big bang model. We discuss cosmological perturbations in these models. In particular we address the issue of matching the perturbations from a collapsing to an expanding phase. We show that, under certain physically motivated and quite generic assumptions on the high energy corrections, one obtains n=0 for the spectrum of scalar perturbations in the original pre-big bang model (with a vanishing potential). With the same assumptions, when an exponential potential for the dilaton is included, a scale invariant spectrum (n=1) of adiabatic scalar perturbations is produced under very generic matching conditions, both in a modified pre-big bang and ekpyrotic scenario. We also derive the resulting spectrum for arbitrary power law scale factors matched to a radiation-dominated era.