Cosmological perturbations in extended massive gravity

Gümrükçüoğlu, A. Emir; Hinterbichler, Kurt; Lin, C.; Mukohyama, Shinji; Trodden, Mark

doi:10.1103/physrevd.88.024023

Cited by 69 publications

(43 citation statements)

References 79 publications

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“…For instance, the problem of vanishing kinetic terms have been addressed in a similar manner in the mass-varying massive gravity [34], where the mass parameters are promoted to functions of a new dynamical field. On the other hand, in order to achieve self-acceleration the mass functions need to vary slowly, making the scalar and vector modes strongly coupled [35]. In contrast, in the present paper, we showed that the scalar perturbations in the GMG theory effectively end up with finite kinetic terms provided that one considers modes that are sub-horizon and below the characteristic GMG length scale.…”

Section: Discussioncontrasting

confidence: 52%

“…With the solution (35) we reduce the quadratic action to a system with 3 degrees of freedom (ψ, E, δϕ). Formally, the action is the following;…”

Section: Scalarsmentioning

confidence: 99%

“…Bimetric cosmology suffers from a gradient type instability [22][23][24][25][26][27][28], although resolutions do exist: a chameleon-like potential [29], screening as the instability takes over [30,31], hierachy between the two coupling constants [32], to name a few. Other extensions where an additional scalar field couples to the mass term provide a new way to achieve cosmology [33,34], although ensuring perturbative stability continues to be a challenge [35][36][37][38].…”

Section: Introductionmentioning

confidence: 99%

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Stable cosmology in generalized massive gravity

2020

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We present a thorough analysis of the cosmological perturbations in Generalised Massive Gravity. This is an extension of de Rham-Gabadadze-Tolley theory where the translation invariance in the Stückelberg field space is broken. This allows the mass parameters to be promoted to functions of the Stückelberg fields. We consider an exact cosmological background in this theory and study the stability of perturbations. We derive conditions to avoid ghost, gradient and tachyonic instability. The cosmology is an extension of the self-accelerating branch of the constant mass parameter theory, but now all five massive graviton polarisations propagate. For concreteness, we consider a minimal version of the theory where cosmology undergoes an accelerated expansion at late times and show that the perturbative stability is preserved for a range of parameters. 1 Approximately FLRW backgrounds may be safe against perturbations [10,11], although the lack of overall homogeneity and/or isotropy poses a technical challenge for obtaining accurate predictions beyond the background level. There also exist exact FLRW solutions that have a spatially isotropic fiducial metric [12,13] but these solutions are likely to be unstable [14].

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Section: Discussioncontrasting

confidence: 52%

“…With the solution (35) we reduce the quadratic action to a system with 3 degrees of freedom (ψ, E, δϕ). Formally, the action is the following;…”

Section: Scalarsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Stable cosmology in generalized massive gravity

2020

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“…These include mass-varying gravity and the quasi-dilaton models [119, 118]. In [281] it was shown that mass-varying gravity and the quasi-dilaton model could allow for stable cosmological solutions but for the original quasi-dilaton theory the self-accelerating solutions are always unstable. On the other hand, the generalizations of the quasi-dilaton [126, 127] appears to allow stable cosmological solutions.…”

Section: Cosmologymentioning

confidence: 99%

Massive Gravity

Rham

2014

Living Rev. Relativ.

1,034

1,062

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We review recent progress in massive gravity. We start by showing how different theories of massive gravity emerge from a higher-dimensional theory of general relativity, leading to the Dvali-Gabadadze-Porrati model (DGP), cascading gravity, and ghost-free massive gravity. We then explore their theoretical and phenomenological consistency, proving the absence of Boulware-Deser ghosts and reviewing the Vainshtein mechanism and the cosmological solutions in these models. Finally, we present alternative and related models of massive gravity such as new massive gravity, Lorentz-violating massive gravity and non-local massive gravity.

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“…(iv) m 2 π ≡ C=A ≥ 0: last, we enforce the mass of the scalar d.o.f. to be real [91], to avoid tachyonic instabilities. In fðRÞ gravity, that we consider in Sec.…”

Section: A Stability Of Perturbations In the Dark Sectormentioning

confidence: 99%

Effective field theory of cosmic acceleration: An implementation in CAMB

et al. 2014

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We implement the effective field theory (EFT) approach to dark energy and modified gravity in the public Einstein-Boltzmann solver CAMB. The resulting code, which we dub EFTCAMB, is a powerful and versatile tool that can be used for several objectives. It can be employed to evolve the full dynamics of linear scalar perturbations of a broad range of single field dark energy and modified gravity model, once the model of interest is mapped into the EFT formalism. It offers a numerical implementation of EFT as a model-independent framework to test gravity on cosmological scales. EFTCAMB has a built-in check for the fulfillment of general stability conditions such as the absence of ghost and superluminal propagation of perturbations. It handles phantom-divide crossing models and does not contain any quasistatic approximation, but rather evolves the full dynamics of perturbations on linear scales. As we will show, the latter is an important feature in view of the accuracy and scale range of upcoming surveys. We show the reliability and applicability of our code by evolving the dynamics of linear perturbations and extracting predictions for power spectra in several models. In particular we perform a thorough analysis of fðRÞ theories, comparing our outputs with those of an existing code for ΛCDM backgrounds, and finding an agreement that can reach 0.1% for models with a Compton wavelength consistent with current cosmological data. We then showcase the flexibility of our code studying two different scenarios. First we produce new results for designer fðRÞ models with a time-varying dark energy equation of state. Second, we extract predictions for linear observables in some parametrized EFT models with a phantom-divide crossing equation of state for dark energy.

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Cosmological perturbations in extended massive gravity

Cited by 69 publications

References 79 publications

Stable cosmology in generalized massive gravity

Stable cosmology in generalized massive gravity

Massive Gravity

Effective field theory of cosmic acceleration: An implementation in CAMB

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