Density perturbations in the ekpyrotic scenario

By J. Khoury, B. Ovrut, Paul J. Steinhardt, N. Turok. 2001

230 citations recorded by the source corpus.

We study the generation of density perturbations in the ekpyrotic scenario for the early universe, including gravitational backreaction. We expose interesting subtleties that apply to both inflationary and ekpyrotic models. Our analysis includes a detailed proposal of how the perturbations generated in a contracting phase may be matched across a ``bounce'' to those in an expanding hot big bang phase. For the physical conditions relevant to the ekpyrotic scenario, we reobtain our earlier result of a nearly scale-invariant spectrum of energy density perturbations. We find that the perturbation amplitude is typically small, as desired to match observation.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/a1d21afa63717316df054494e7941d80c74cb558

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

1. Robert Brandenberger
2. Yi-Fu Cai
3. Andrei Linde
4. P. Peter
5. J. Khoury
6. D. Baumann
7. J. Lehners
8. L. Senatore

In Nuclear and High Energy Physics

1. Yi-Fu Cai
2. Robert Brandenberger
3. Andrei Linde
4. P. Peter
5. J. Khoury
6. J. Lehners
7. D. Baumann
8. L. Senatore

Citations in the corpus

• Bouncing Cosmologies: Progress and Problems (2016, background): “which leads to a scale-invariant spectrum of u and Φ fluctuations on super-Hubble scales in the contracting phase, as initially expected in [48].”
• New Ekpyrotic Cosmology (2007, unknown): “tonian gauge. It is convenient to do the analysis in terms of a related gauge-invariant variable, u ≡ a�/φ′, where primes denote differentiation with respect to conformal time τ. Its Fourier modes satisfy [ 3 ]”
• Cosmology with negative potentials (2002, methodology): “The spectrum of density perturbations obtained in [ 14 ] is not blue, as in [11], but red, like in the pyrotechnic scenario [12] and in the simplest versions of chaotic inflation.”
• Galileon Cosmology (2009, background): “This could naturally match onto an ekpyrotic [30, 31, 32, 33, 34], New Ekpyrotic [35, 36, 37, 38, 39] or cyclic [40, 41] contracting phase, for instance.”
• Nonsingular cosmology with a scale-invariant spectrum of cosmological perturbations from Lee-Wick theory (2008, background): “Since our bounce is non-singular, the computation of the evolution of fluctuations is free of the matching condition ambiguities which affect the study of fluctuations in singular bouncing cosmologies such as the Ekpyrotic scenario (see [26, 27, 28, 29, 30, 31] for some early papers on the problem o”
• A smooth bouncing cosmology with scale invariant spectrum (2007, background): “(10) We thus reach the conclusion that, in the absence of gravity, a field moving along any negative exponential potential generates a scale invariant spectrum of perturbations [22].”
• Ekpyrotic and cyclic cosmology (2008, background): “The single-field scalar perturbation theory was first discussed in [48,49].”
• The Matter Bounce Alternative to Inflationary Cosmology (2012, result): “[48] J.”