Abstract
We 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 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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ArXiv ePrint: 1202.3131
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Deruelle, N., Sasaki, M., Sendouda, Y. et al. Lorentz-violating vs. ghost gravitons: the example of Weyl gravity. J. High Energ. Phys. 2012, 9 (2012). https://doi.org/10.1007/JHEP09(2012)009
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DOI: https://doi.org/10.1007/JHEP09(2012)009