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arXiv · 2102.03818

Nearly scale-invariant curvature modes from entropy perturbations during graceful exit

Anna Ijjas·Roman Kolevatov
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Abstract

In this Letter, we describe how a spectrum of entropic perturbations generated during a period of slow contraction can source a nearly scale-invariant spectrum of curvature perturbations on length scales larger than the Hubble radius during the transition from slow contraction to a classical non-singular bounce (the `graceful exit' phase). The sourcing occurs naturally through higher-order scalar field kinetic terms common to classical (non-singular) bounce mechanisms. We present a concrete example in which, by the end of the graceful exit phase, the initial entropic fluctuations have become negligible and the curvature fluctuations have a nearly scale-invariant spectrum with an amplitude consistent with observations.

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Anna Ijjas, Roman Kolevatov. 2021-02-07. Nearly scale-invariant curvature modes from entropy perturbations during graceful exit. https://doi.org/10.1103/physrevd.103.l101302

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