Low energy ghosts and the Jeans’ instability

A. Emir Gumrukcuoglu, Shinji Mukohyama, Thomas P. Sotiriou

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We show that a massless canonical scalar field minimally coupled to general relativity can become a tachyonic ghost at low energies around a background in which the scalar's gradient is spacelike. By performing a canonical transformation we demonstrate that this low energy ghost can be recast, at the level of the action, in a form of a fluid that undergoes a Jeans-like instability affecting only modes with large wavelength. This illustrates that low-energy tachyonic ghosts do not lead to a catastrophic quantum vacuum instability, unlike the usual high-energy ghost degrees of freedom.
Original languageEnglish
Article number064001
JournalPhysical Review D
Issue number6
Early online date1 Sept 2016
Publication statusPublished - 15 Sept 2016
Externally publishedYes


  • hep-th
  • gr-qc
  • RCUK
  • STFC
  • ST/L00044X/1


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