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Lorentz-violating vs. ghost gravitons: the example of Weyl gravity
Deruelle N., Sasaki M., Sendouda Y., Youssef A.
Journal of High Energy Physics 09 (2012) 009 - http://hal.archives-ouvertes.fr/hal-00740758
Physique/Relativité Générale et Cosmologie Quantique
Physique/Physique des Hautes Energies - Théorie
Lorentz-violating vs. ghost gravitons: the example of Weyl gravity
N. Deruelle1, M. Sasaki2, Y. Sendouda1, A. Youssef
1 :  APC - UMR 7164 - AstroParticule et Cosmologie
CNRS : UMR7164 – IN2P3 – Observatoire de Paris – Université Paris VII - Paris Diderot – CEA : DSM/IRFU
APC - UMR 7164, Université Paris Diderot, 10 rue Alice Domon et Léonie Duquet, case postale 7020, F-75205 Paris Cedex 13
2 :  Yukawa Institute for Theoretical Physics
University of Kyoto
Kyoto University, Kyoto 606-8502
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.

Journal of High Energy Physics
Publisher Institute of Physics (IOP)
ISSN 1126-6708 (eISSN : 1029-8479)
Articles dans des revues avec comité de lecture

Cosmology of Theories beyond the SM – Models of Quantum Gravity – Classical Theories of Gravity
14 pages, 3 figures, REVTeX 4.1

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