Generating Ekpyrotic Curvature Perturbations Before the Big Bang

By J. Lehners, Paul McFadden, N. Turok, Paul J. Steinhardt. 2007

192 citations recorded by the source corpus.

We analyze a general mechanism for producing a nearly scale-invariant spectrum of cosmological curvature perturbations during a contracting phase preceding a big bang, which can be entirely described using 4D effective field theory. The mechanism, based on first producing entropic perturbations and then converting them to curvature perturbations, can be naturally incorporated in cyclic and ekpyrotic models in which the big bang is modeled as a brane collision, as well as other types of cosmological models with a pre-big bang phase. We show that the correct perturbation amplitude can be obtained and that the spectral tilt n{sub s} tends to range from slightly blue to red, with 0.97<n{sub s}<1.02 for the simplest models, a range compatible with current observations but shifted by a few percent towards the blue compared to the prediction of the simplest, large-field inflationary models.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/9f168aa76c317f35fb8b30d8a07736da557b5633

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Citations in the corpus

The Matter Bounce Alternative to Inflationary Cosmology (2012, background): “Calculations done in the higher-dimensional framework of the Ekpyrotic scenario show that modes which from the four space-time dimensional point of view are entropy modes can mediate a successful transition of the spectrum across the Ekpyrotic bounce [55] (see also [56–58]).”
CMB at 2 × 2 order: the dissipation of primordial acoustic waves and the observable part of the associated energy release (2012, background): “However, given the large variety of inflationary models (some examples of possible interest are Mukhanov & Chibisov 1981; Silk & Turner 1987; Salopek et al. 1989; Lehners et al. 2007; Ben-Dayan & Brustein 2010; Barnaby et al. 2012), the energy release in theµ- andy-era can differ by a large amount.”
New Ekpyrotic Cosmology (2007, unknown): “turbations for the above scaling solution [ 24 , 27].”
Rapidly-Varying Speed of Sound, Scale Invariance and Non-Gaussian Signatures (2008, methodology): “This has been shown to occur, for example, in the slowly contracting background of the new ekpyrotic cosmology [3, 4, 5, 6, 7, 8] or in the kinetic dominated pre-big bang cosmology [9, 10].”
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): “In fact, in the case of the Ekpyrotic scenario (which is intrinsically a higherdimensional cosmology), computations done in the higher dimensional framework yielded a successful transfer of the scale-invariant spectrum of metric fluctuations from the contracting to the expanding phase [60], a conclu”
On the consistency relation of the three-point function in single-field inflation (2007, background): “Outside of the inflationary paradigm, the recently proposed new bouncing cosmology [7]–[9], though less compelling than inflation, predicts a potentially detectable non-Gaussian signal that violates the consistency relation [9].”
Ekpyrotic and cyclic cosmology (2008, methodology): “We will now discuss the various possibilities considered in the literature, namely conversion after the ekpyrotic phase during kinetic energy domination [61], conversion during the ekpyrotic phase [57,56] or during the transition to a ghost condensate phase [22,30], and conversion after the big bang”
An infinite set of Ward identities for adiabatic modes in cosmology (2013, background): “Conversely, to observe a significant 3-point function in this limit requires violating one of the assumptions above, for instance through additional scalar fields [23–28] or an unstable background [29, 30, 33, 34].”