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Scale separation, rolling solutions, and entropy bounds

David Andriot1, Niccolò Cribiori2, and Thomas Van Riet2

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Phys. Rev. D 112, 026028 – Published 28 July, 2025

DOI: https://doi.org/10.1103/5rkw-5qfk

Abstract

We revisit scale separation for compactifications of ten- and eleven-dimensional supergravity. For cosmological solutions rolling down flux-generated potentials, we observe that scale separation is achieved as time flows, and is fairly generic. This is realized without the need of orientifolds nor corrections to the classical supergravity approximation. We then confront scale separation with the covariant entropy bound (CEB) and the Cohen-Kaplan-Nelson bound. We show that a naive application of these bounds to vacua hints at the existence of at least two extra dimensions. For rolling solutions, we observe that the CEB is not always respected, but since these examples lack a cosmic horizon, the application of entropy bounds remains delicate.

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Phys. Rev. D 112, 026028– Published 28 July, 2025
  • Received 28 April 2025
  • Accepted 7 July 2025
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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. Funded by SCOAP3.

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