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

@article{Deruelle2012LorentzviolatingVG,
  title={Lorentz-violating vs. ghost gravitons: the example of Weyl gravity},
  author={Nathalie Deruelle and Misao Sasaki and Yuuiti Sendouda and Ahmed Youssef},
  journal={Journal of High Energy Physics},
  year={2012},
  volume={2012},
  pages={1-21}
}
A bstractWe show that the ghost degrees of freedom of Einstein gravity with a Weyl term can be tamed 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… 
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