On the Extra Mode and Inconsistency of Horava Gravity

Blas, D.; Pujolas, O.; Sibiryakov, S.

doi:10.48550/arxiv.0906.3046

Cited by 157 publications

(359 citation statements)

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“…Note added: When this paper was reviewed, we were informed that another paper [10] holds a different opinion on the constraint structure in Hořava-Lifshitz theory. We disagree with the result in [10] for the following reason.…”

Section: Discussionmentioning

confidence: 99%

A trouble with Hořava-Lifshitz gravity

Pang

2009

J. High Energy Phys.

162

187

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We study the structure of the phase space in Hořava-Lifshitz theory. With the constraints derived from the action, the phase space is described by five fields, thus there is a lack of canonical structure. The Poisson brackets of the Hamiltonian density do not form a closed structure, resulting in many new constraints. Taking these new constraints into account, it appears that there is no degree of freedom left, or the phase space is reduced to one with an odd number of fields.1 Some papers also pointed out the problem related to cosmological constant [6,7].

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Section: Discussionmentioning

confidence: 99%

A trouble with Hořava-Lifshitz gravity

Pang

2009

J. High Energy Phys.

162

187

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“…The fact that for ξ = 0 the scalar mode can be eliminated at the level of linear perturbations does not necessarily mean it is absent altogether. 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[56,57,58]. Note also that the linear expansion mode found for the ξ = 0 non-projectable case need not be physical.…”

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confidence: 97%

Quantum gravity without Lorentz invariance

Sotiriou

Visser

Weinfurtner

2009

J. High Energy Phys.

282

312

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There has been a significant surge of interest in Hořava's model for 3+1 dimensional quantum gravity, this model being based on anisotropic scaling at a z = 3 Lifshitz point. Hořava's model, and its variants, show dramatically improved ultraviolet behaviour at the cost of exhibiting violation of Lorentz invariance at ultrahigh momenta. Following up on our earlier note, Phys. Rev. Lett. 102 (2009) 251601 [arXiv:0904.4464 [hep-th]], we discuss in more detail our variant of Hořava's model. In contrast to Hořava's original model, we abandon "detailed balance" and restore parity invariance. We retain, however, Hořava's "projectability condition" and explore its implications. Under these conditions, we explicitly exhibit the most general model, and extract the full classical equations of motion in ADM form. We analyze both spin-2 and spin-0 graviton propagators around flat Minkowski space. We furthermore analyze the classical evolution of FLRW cosmologies in this model, demonstrating that the higher-derivative spatial curvature terms can be used to mimic radiation fluid and stiff matter. We conclude with some observations concerning future prospects.

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“…Models similar Mimetic Dark Matter to also appear in the IR limit of the projectable version of Hořava-Lifshitz gravity [7][8][9] and correspond to a scalar version of the so-called Einstein Aether [10]. Surprisingly these models can also emerge in the non-commutative geometry [11].…”

Section: Introduction and Discussionmentioning

confidence: 99%

Many Faces of Mimetic Gravity

Hammer,

Vikman

2015

Preprint

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We consider the recently introduced mimetic gravity, which is a Weyl-symmetric extension of the General Relativity and which can play a role of an imperfect fluid-like Dark Matter with a small sound speed. In this paper we discuss in details how this higherderivative scalar-tensor theory goes beyond the construction by Horndeski, keeping only one scalar degree of freedom on top of two standard graviton polarizations. In particular, we consider representations of the theory in different sets of Weyl-invariant variables and connect this framework to the singular Brans-Dicke theory. Further, we find solution of equations of motion for the mimetic gravity in the synchronous reference frame in a general curved spacetime. This solution is exact in the test-field approximation or in the case of a shear-free spacetime without any other matter.

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On the Extra Mode and Inconsistency of Horava Gravity

Cited by 157 publications

References 0 publications

A trouble with Hořava-Lifshitz gravity

A trouble with Hořava-Lifshitz gravity

Quantum gravity without Lorentz invariance

Many Faces of Mimetic Gravity

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