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arXiv · 1202.3131

Lorentz-violating vs ghost gravitons: the example of Weyl gravity

Nathalie Deruelle·Misao Sasaki·Yuuiti Sendouda·Ahmed Youssef
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Abstract

We show that the ghost degrees of freedom of Einstein gravity with a Weyl term can be eliminated by a simple mechanism that invokes local Lorentz symmetry breaking. We demonstrate how the mechanism works in a cosmological setting. The presence of the Weyl term forces a redefinition of the quantum vacuum state of the tensor perturbations. As a consequence the amplitude of their spectrum blows up when the Lorentz-violating scale becomes comparable to the Hubble radius. Such a behaviour is in sharp contrast to what happens in standard Weyl gravity where the gravitational ghosts smoothly damp out the spectrum of primordial gravitational waves.

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Nathalie Deruelle, Misao Sasaki, Yuuiti Sendouda, Ahmed Youssef. 2012-02-14. Lorentz-violating vs ghost gravitons: the example of Weyl gravity. https://doi.org/10.1007/jhep09(2012)009

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