Massive cosmological scalar perturbations

Khosravi, Nima; Sepangi, H. R.; Shahidi, Shahab

doi:10.1103/physrevd.86.043517

Cited by 52 publications

(46 citation statements)

References 44 publications

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“…First note that the determinant is always negative if ω < 0. Along with the condition for a realistic cosmology obtained from (18), the range of allowed ω is thus…”

Section: Perturbationsmentioning

confidence: 99%

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Cosmological perturbations in extended massive gravity

et al. 2013

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We study cosmological perturbations around self-accelerating solutions to two extensions of nonlinear massive gravity: the quasi-dilaton theory and the mass-varying theory. We examine stability of the cosmological solutions, and the extent to which the vanishing of the kinetic terms for scalar and vector perturbations of self-accelerating solutions in massive gravity is generic when the theory is extended. We find that these kinetic terms are in general non-vanishing in both extensions, though there are constraints on the parameters and background evolution from demanding that they have the correct sign. In particular, the self-accelerating solutions of the quasi-dilaton theory are always unstable to scalar perturbations with wavelength shorter than the Hubble length.

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“…First note that the determinant is always negative if ω < 0. Along with the condition for a realistic cosmology obtained from (18), the range of allowed ω is thus…”

Section: Perturbationsmentioning

confidence: 99%

“…Finally, on the self-accelerating solutions, with constant H specified by (18), the equation of motion for σ fixes the ratio r = a/N . From Eq.…”

Section: B Self-accelerating Background Solutionsmentioning

confidence: 99%

Cosmological perturbations in extended massive gravity

et al. 2013

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“…In this paper we will work mostly with this Hassan-Rosen bimetric theory. For related work, see [40][41][42][43][44][45][46][47][48][49][50][51][52].…”

Section: Background To Bimetric Theoriesmentioning

confidence: 99%

On consistent theories of massive spin-2 fields coupled to gravity

Hassan

Schmidt-May

Strauss

2013

J. High Energ. Phys.

125

177

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We consider the issues that arise out of interpreting the ghost-free bimetric theory as a theory of a spin-2 field coupled to gravity. This requires identifying a gravitational metric and parameterizing deviations of the resulting theory from general relativity. To this end, we first consider the most general bimetric backgrounds for which a massless and a massive spin-2 fluctuation exist, and we compute the most general expression for the Fierz-Pauli mass. These backgrounds coincide with solutions in general relativity. Based on this, we obtain nonlinear extensions of the massive and massless spin-2 fields. The background value of the nonlinear massive field parameterizes generic deviations of the bimetric theory from GR. It is also shown that the most natural nonlinear massless field does not have standard ghost-free matter couplings, and hence cannot represent the gravitational metric. However, an appropriate gravitational metric can still be identified in the weak gravity limit. Hence in the presence of other neutral spin-2 fields, the weak gravity limit is crucial for compatibility with general relativity. We also write down the action in terms of the nonlinear massive spin-2 field and obtain its ghost-free couplings to matter. The discussion is then generalized to multimetric theories.

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“…However, linear perturbations, studied extensively in Refs. [48][49][50][51][52][53][54][55][56][57][58][59][60][61][62], tend to contain either ghost or gradient instabilities. In each of these cases there are potential ways out.…”

Section: Introductionmentioning

confidence: 99%

Cosmology with three interacting spin-2 fields

et al. 2016

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Theories of massive gravity with one or two dynamical metrics generically lack stable and observationally-viable cosmological solutions that are distinguishable from ΛCDM. We consider an extension to trimetric gravity, with three interacting spin-2 fields which are not plagued by the Boulware-Deser ghost. We systematically explore every combination with two free parameters in search of background cosmologies that are competitive with ΛCDM. For each case we determine whether the expansion history satisfies viability criteria, and whether or not it contains beyond-ΛCDM phenomenology. Among the many models we consider, there are only three cases that seem to be both viable and distinguishable from standard cosmology. One of the models has only one free parameter and displays a crossing from above to below the phantom divide. The other two provide scaling behavior, although they contain future singularities that need to be studied in more detail. These models possess interesting features that make them compelling targets for a full comparison to observations of both cosmological expansion history and structure formation.

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Massive cosmological scalar perturbations

Cited by 52 publications

References 44 publications

Cosmological perturbations in extended massive gravity

Cosmological perturbations in extended massive gravity

On consistent theories of massive spin-2 fields coupled to gravity

Cosmology with three interacting spin-2 fields

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