A trouble with Hořava-Lifshitz gravity

Li, Miao; Pang, Yi

doi:10.1088/1126-6708/2009/08/015

Cited by 162 publications

(197 citation statements)

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“…Indeed, whenever Þ 0 the lapse N is no longer a Lagrange multiplier, and the Hamiltonian constraint (obtained as the variation of the action with respect to N, H S N ¼ 0) together with the equation N ¼ 0 form a pair of second-class constraints (they have a nonvanishing Poisson bracket), which can be used to eliminate N and N . Hence, the pathologies [6,15] present in Hořava's original proposal do not appear.…”

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confidence: 93%

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Consistent Extension of Hořava Gravity

2010

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We propose a natural extension of Hořava's model for quantum gravity, which is free from the notorious pathologies of the original proposal. The new model endows the scalar graviton mode with a regular quadratic action and remains power-counting renormalizable. At low energies, it reduces to a Lorentzviolating scalar-tensor gravity theory. The deviations with respect to general relativity can be made weak by an appropriate choice of parameters. Introduction.-Recently, Hořava has proposed a new approach to quantum gravity [1]. The key idea is to abandon local Lorentz invariance as fundamental and to assume instead that it appears at low energies as an approximate symmetry. The breaking of Lorentz invariance is achieved by equipping the space-time with a preferred foliation by three-dimensional spacelike surfaces, which defines the splitting of coordinates into space and time. This allows us to complete the action of general relativity (GR) with higher spatial derivatives of the metric, improving the UV behavior of the graviton propagator and making the theory power-counting renormalizable. Besides, the action remains second order in time derivatives, avoiding the ghosts of covariant theories of higher-derivative gravity [2].The concrete realization of this idea as developed in [1] unfolds as follows. One considers the 3 þ 1 decomposition of the space-time metric in the preferred foliation,

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confidence: 93%

“…The pathologies include strong coupling at energies above a very low-energy scale and fast instabilities, and appear both in the nonprojectable [5][6][7] and projectable [7][8][9] cases. These problems can be traced back to the anomalous structure of the quadratic action for the new scalar mode around smooth backgrounds, such as Minkowski space-time.…”

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confidence: 99%

Consistent Extension of Hořava Gravity

2010

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“…It can be shown that only the sixth-order derivative terms in the potential are more than 60 [27]. It should be also noted that giving up the projectability condition often causes the theory to suffer the inconsistence problem [36]. However, Kluson recently showed that the Hamiltonian formalism of the BPS model is very rich, and that the algebra of constraints is well-defined [37].…”

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confidence: 99%

Stability of spin-0 graviton and strong coupling in Horava-Lifshitz theory of gravity

Wang

2011

Phys. Rev. D

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In this paper, we consider two different issues, stability and strong coupling, raised lately in the newly-proposed Horava-Lifshitz (HL) theory of quantum gravity with projectability condition. We find that all the scalar modes are stable in the de Sitter background, due to two different kinds of effects, one from high-order derivatives of the spacetime curvature, and the other from the exponential expansion of the de Sitter space. Combining these effects properly, one can make the instability found in the Minkowski background never appear even for small-scale modes, provided that the IR limit is sufficiently closed to the relativistic fixed point. At the fixed point, all the modes become stabilized. We also show that the instability of Minkowski spacetime can be cured by introducing mass to the spin-0 graviton. The strong coupling problem is investigated following the effective field theory approach, and found that it cannot be cured by the Blas-Pujolas-Sibiryakov mechanism, initially designed for the case without projectability condition, but might be circumvented by the Vainshtein mechanism, due to the non-linear effects. In fact, we construct a class of exact solutions, and show explicitly that it reduces smoothly to the de Sitter spacetime in the relativistic limit.PACS numbers: 98.80.Cq; 98.80.Bp

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“…Thus, this theory leads to a modification of the Einstein's general relativity at high energies producing interesting features in cosmology. Furthermore Horava-Lifshitz gravity has been studied and extended in detail [29][30][31][32][33][34][35][36] and applied as a cosmological frame work of the universe [37][38][39][40][41][42][43][44][45][46]. Recently, different dark energy models have been studied in the framework of Horava-Lifshitz cosmology using different infrared cut-offs.…”

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confidence: 99%

Generalized ghost dark energy in Horava–Lifshitz cosmology

Borah

Ansari

2014

J Theor Appl Phys

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Purpose of this paper is to study generalized quantum chromodynamics ghost dark energy (GDE) in the frame work of Horava-Lifshitz cosmology. Considering interacting and non-interacting scenario of GDE with dark matter in a spatially non-flat universe, we investigate the cosmological implications of this model in detail. We obtain equation of state parameter, deceleration parameter and the evolution of dark energy density to explain the expansion of the universe. Also, we show that the results we calculate have a good compatibility with previous work and restore it in limiting case. Further, we investigate validity of generalized second law of thermodynamics in this scenario. Finally, we find out a cosmological application of our work by evaluating a relation for the equation of state of dark energy for law redshifts.

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A trouble with Hořava-Lifshitz gravity

Cited by 162 publications

References 15 publications

Consistent Extension of Hořava Gravity

Consistent Extension of Hořava Gravity

Stability of spin-0 graviton and strong coupling in Horava-Lifshitz theory of gravity

Generalized ghost dark energy in Horava–Lifshitz cosmology

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