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Strong coupling in Ho?ava gravity

Charmousis, Christos; Niz, Gustavo; Padilla, Antonio; Saffin, Paul M.

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Christos Charmousis

Gustavo Niz

Professor of Physics


By studying perturbations about the vacuum, we show that Horava gravity suffers from two different strong coupling problems, extending all the way into the deep infra-red. The first of these is associated with the principle of detailed balance and explains why solutions to General Relativity are typically not recovered in models that preserve this structure. The second of these occurs even without detailed balance and is associated with the breaking of diffeomorphism invariance, required for anisotropic scaling in the UV. Since there is a reduced symmetry group there are additional degrees of freedom, which need not decouple in the infra-red. Indeed, we use the Stuckelberg trick to show that one of these extra modes become strongly coupled as the parameters approach their desired infra-red fixed point. Whilst we can evade the first strong coupling problem by breaking detailed balance, we cannot avoid the second, whatever the form of the potential. Therefore the original Horava model, and its "phenomenologically viable" extensions do not have a perturbative General Relativity limit at any scale. Experiments which confirm the perturbative gravitational wave prediction of General Relativity, such as the cumulative shift of the periastron time of binary pulsars, will presumably rule out the theory.


Charmousis, C., Niz, G., Padilla, A., & Saffin, P. M. (2009). Strong coupling in Ho?ava gravity. Journal of High Energy Physics, 2009(8),

Journal Article Type Article
Acceptance Date Aug 5, 2009
Publication Date Aug 19, 2009
Deposit Date Apr 21, 2017
Publicly Available Date Apr 21, 2017
Journal Journal of High Energy Physics
Electronic ISSN 1029-8479
Publisher Springer Verlag
Peer Reviewed Peer Reviewed
Volume 2009
Issue 8
Public URL
Publisher URL


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