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On the ghost-induced instability on de Sitter background

Authors
  • Peter, Patrick
  • Salles, Filipe de O.
  • Shapiro, Ilya L.
Type
Published Article
Publication Date
Jan 03, 2018
Submission Date
Dec 29, 2017
Identifiers
DOI: 10.1103/PhysRevD.97.064044
Source
arXiv
License
Yellow
External links

Abstract

It is known that the perturbative instability of tensor excitations in higher derivative gravity may not take place if the initial frequency of the gravitational waves are below the Planck threshold. One can assume that this is a natural requirement if the cosmological background is sufficiently mild, since in this case the situation is qualitatively close to the free gravitational wave in flat space. Here, we explore the opposite situation and consider the effect of a very far from Minkowski radiation-dominated or de Sitter cosmological background with a large Hubble rate, e.g., typical of an inflationary period. It turns out that, then, for initial Planckian or even trans-Planckian frequencies, the instability is rapidly suppressed by the very fast expansion of the universe.

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