New Ekpyrotic Cosmology

Loading...
Thumbnail Image
Penn collection
Department of Physics Papers
Degree type
Discipline
Subject
Physical Sciences and Mathematics
Physics
Funder
Grant number
License
Copyright date
Distributor
Related resources
Author
Buchbinder, Evgeny I.
Contributor
Abstract

In this paper, we present a new scenario of the early universe that contains a pre-big bang ekpyrotic phase. By combining this with a ghost condensate, the theory explicitly violates the null energy condition without developing any ghostlike instabilities. Thus the contracting universe goes through a nonsingular bounce and evolves smoothly into the expanding post-big bang phase. The curvature perturbation acquires a scale-invariant spectrum well before the bounce in this scenario. It is sourced by the scale-invariant entropy perturbation engendered by two ekpyrotic scalar fields, a mechanism recently proposed by Lehners et al. Since the background geometry is nonsingular at all times, the curvature perturbation remains nearly constant on superhorizon scales. It emerges from the bounce unscathed and imprints a scale-invariant spectrum of density fluctuations in the matter-radiation fluid at the onset of the hot big bang phase. The ekpyrotic potential can be chosen so that the spectrum has a red tilt, in accordance with the recent data from WMAP. As in the original ekpyrotic scenario, the model predicts a negligible gravity wave signal on all observable scales. As such ‘‘new ekpyrotic cosmology’’ provides a consistent and distinguishable alternative to inflation to account for the origin of the seeds of large-scale structure.

Advisor
Date Range for Data Collection (Start Date)
Date Range for Data Collection (End Date)
Digital Object Identifier
Series name and number
Publication date
2007-12-07
Journal title
Volume number
Issue number
Publisher
Publisher DOI
Journal Issue
Comments
Suggested Citation: E.I. Buchbinder, J. Khoury and B.A. Ovrut. (2007). "New ekpyrotic cosmology." Physical Review D. 76, 123503. © 2007 The American Physical Society http://dx.doi.org/10.1103/PhysRevD.76.123503
Recommended citation
Collection