Jeans' Ghost
A. Emir Gumrukcuoglu, Shinji Mukohyama, Thomas P. Sotiriou

TL;DR
The paper demonstrates that a massless scalar field coupled to gravity can exhibit a low-energy tachyonic ghost, which manifests as a Jeans-like instability in large-wavelength modes, without causing quantum vacuum instability.
Contribution
It reveals that low-energy tachyonic ghosts can be reinterpreted as fluid instabilities, challenging the notion that all ghosts lead to catastrophic quantum instabilities.
Findings
Identifies conditions for a scalar field to become a tachyonic ghost.
Shows the ghost can be recast as a fluid with Jeans-like instability.
Demonstrates low-energy ghosts do not necessarily cause vacuum instability.
Abstract
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.
Peer Reviews
No public reviews on file for this paper yet. If you reviewed it on a platform where reviews are public (OpenReview, ICLR, NeurIPS, ICML), you can paste yours below so the community can read it here.
Videos
No videos yet. Explain this paper in a talk, walkthrough, or lecture? Add one.
