On the Spectrum of Fluctuations in an Effective Field Theory of the Ekpyrotic Universe

By Robert Brandenberger, F. Finelli. 2001

151 citations recorded by the source corpus.

We consider the four-dimensional effective field theory which has been used in previous studies of perturbations in the Ekpyrotic Universe, and discuss the spectrum of cosmological fluctuations induced on large scales by quantum fluctuations of the bulk brane. By matching cosmological fluctuations on a constant energy density hypersurface we show that the growing mode during the very slow collapsing pre-impact phase couples only to the decaying mode in the expanding post-impact phase, and that hence no scale-invariant spectrum of adiabatic fluctuations is generated. Note that our conclusions may not apply to improved toy models for the Ekpyrotic scenario.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/08ce34e88575bd15af49eb65dcb48b5e84ee1004

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Citations in the corpus

The Matter Bounce Alternative to Inflationary Cosmology (2012, background): “The spectrum of adiabatic fluctuations in the Ekpyrotic scenario is blue [51, 52], and hence additional inputs (e.”
Cosmology and Fundamental Physics with the Euclid Satellite (2012, background): “Leaving aside the problem of the realization of the bounce, it has been shown that the adiabatic mode in this model generically leads to a steep blue spectrum for the curvature perturbations [792, 230, 351].”
A smooth bouncing cosmology with scale invariant spectrum (2007, unknown): “Unfortunately the result is not scale-invariant [12, 13, 14, 11].”
Towards a nonsingular bouncing cosmology (2012, background): “This result agrees with previous studies of artificially smoothed out four-dimensional toy models of Ekpyrotic cosmology [34, 35, 65] (9).”
Bouncing Cosmologies: Progress and Problems (2016, background): “[48] D.”
Ekpyrotic and cyclic cosmology (2008, background): “In light of the ambiguities discussed above, two broadly different attitudes can be adopted (see [10,20,29,34,45,74,76,77,98,99,102] for many discussions of these “matching conditions” in the literature):”
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”