Strong coupling in Horava gravity

By C. Charmousis, G. Niz, Antonio Padilla, P. Saffin. 2009

332 citations recorded by the source corpus.

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.

Subfields: Astronomy and Astrophysics, Oceanography

View Paper: https://www.semanticscholar.org/paper/4d9657250c6b4e2b9f3d0fa2954578730fdb47c0

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Citations in the corpus

Dark matter as integration constant in Horava-Lifshitz gravity (2009, unknown): “Note that a strong self-coupling of the scalar graviton reported in [35] is not a problem if there is a phenomenon analogous to Vainshtein effect [44] since, unlike massive gravity [45] (6), Hořava-Lifshitz gravity is supposed to be UV complete.”
Modified Gravity and Cosmology (2011, background): “To reduce the number of terms, Hořava originally borrowed the notion of detailed balance from condensed matter theory [619], but this has since been shown to lead to phenomenological problems [278, 1169, 1170].”
Quantum gravity without Lorentz invariance (2009, methodology): “Subsequent to the original appearance of this article, several papers have discussed this issue — as well as further difficulties that arise beyond the linearized level [56–58].”
General covariance in quantum gravity at a Lifshitz point (2010, methodology): “It has been applied to the models of gravity with anisotropic scaling [1,2] in [7,12,13].”
Relativistic Quantum Gravity at a Lifshitz Point (2009, background): “Although in the analysis of [20] care has been given to restore the full fourdimensional diffeomorphism invariance in the gravity sector (so that ∇αT grav = 0 holds), the matter sector is not invariant under four-dimensional diffeomorphisms making the reported strong coupling problem of Hořava gravi”
A dynamical inconsistency of Horava gravity (2009, methodology): “In particular, we will not use the “detailed balance” condition which has been shown to be problematic for example for standard black hole solutions [3] (see also [4]).”
The black hole and cosmological solutions in IR modified Hořava gravity (2009, background): “Since then various aspects and solutions have been studied [3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29].”