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arXiv · 1109.0448

Tilted Ekpyrosis

José Fonseca·David Wands
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Abstract

We consider a simple model of cosmological collapse driven by canonical fields with exponential potentials. We generalise the two-field ekpyrotic collapse to consider non-orthogonal or tilted potentials and give the general condition for isocurvature field fluctuations to have a scale-invariant spectrum in this model. In particular we show that tilted potentials allow for a slightly red spectrum of perturbations as required by current observations. However a red spectrum of fluctuations implies that the two-field ekpyrotic phase must have a finite duration and requires a preceding phase which sets the initial conditions for what otherwise appears to be a fine-tuned trajectory in the phase space.

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José Fonseca, David Wands. 2011-09-02. Tilted Ekpyrosis. https://doi.org/10.1103/physrevd.84.101303

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