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  • Letter
  • Open Access

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

Anna Ijjas1,2,* and Roman Kolevatov3

  • 1Max Planck Institute for Gravitational Physics (Albert Einstein Institute), 30167 Hannover, Germany
  • 2Institute for Gravitational Physics, Leibniz University Hannover, 30167 Hannover, Germany
  • 3Department of Physics, Princeton University, Princeton, New Jersey 08544, USA

  • *anna.ijjas@aei.mpg.de
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Phys. Rev. D 103, L101302 – Published 20 May, 2021

DOI: https://doi.org/10.1103/PhysRevD.103.L101302

Abstract

In this paper 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 nonsingular bounce (the “graceful exit” phase). The sourcing occurs naturally through higher-order scalar field kinetic terms common to classical (nonsingular) 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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Phys. Rev. D 103, L101302– Published 20 May, 2021
  • Received 14 March 2021
  • Accepted 22 April 2021
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Open access publication funded by the Max Planck Society.

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