A spectre is haunting the cosmos: quantum stability of massive gravity with ghosts

Könnig, Frank; Nersisyan, Henrik; Akrami, Yashar; Amendola, Luca; Zumalacárregui, Miguel

doi:10.1007/jhep11(2016)118

Cited by 17 publications

(22 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…If the initial conditions for h g and h f are similar, then the source terms (30) are negligible at early times, i.e. small a, and the equations decouple.…”

Section: B Radiation and Matter Dominated Eramentioning

confidence: 99%

Surfing gravitational waves: can bigravity survive growing tensor modes?

Amendola

Könnig

Martinelli

et al. 2015

J. Cosmol. Astropart. Phys.

Self Cite

View full text Add to dashboard Cite

The theory of bigravity offers one of the simplest possibilities to describe a massive graviton while having self-accelerating cosmological solutions without a cosmological constant. However, it has been shown recently that bigravity is affected by early-time fast growing modes on the tensor sector. Here we argue that we can only trust the linear analysis up to when perturbations are in the linear regime and use a cut-off to stop the growing of the metric perturbations. This analysis, although more consistent, still leads to growing tensor modes that are unacceptably large for the theory to be compatible with measurements of the cosmic microwave background (CMB), both in temperature and polarization spectra. In order to suppress the growing modes and make the model compatible with CMB spectra, we find it necessary to either fine-tune the initial conditions, modify the theory or set the cut-off for the tensor perturbations of the second metric much lower than unity. Initial conditions such that the growing mode is sufficiently suppresed can be achieved in scenarios in which inflation ends at the GeV scale.

show abstract

“…If the initial conditions for h g and h f are similar, then the source terms (30) are negligible at early times, i.e. small a, and the equations decouple.…”

Section: B Radiation and Matter Dominated Eramentioning

confidence: 99%

Surfing gravitational waves: can bigravity survive growing tensor modes?

Amendola

Könnig

Martinelli

et al. 2015

J. Cosmol. Astropart. Phys.

Self Cite

View full text Add to dashboard Cite

show abstract

“…The second category approach is by modified general relativity including Horndeski's types such as galileons, chameleons, Brans-Dicke, symmetrons, and other possibilities. In the third strategy, based on a thermodynamics point of view, phenomenological exotic fluids are supposed for an alternative dark energy model [4][5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Non-minimal derivative coupling scalar field and bulk viscous dark energy

2017

View full text Add to dashboard Cite

Inspired by thermodynamical dissipative phenomena, we consider bulk viscosity for dark fluid in a spatially flat two-component Universe. Our viscous dark energy model represents phantom-crossing which avoids bigrip singularity. We propose a non-minimal derivative coupling scalar field with zero potential leading to accelerated expansion of the Universe in the framework of bulk viscous dark energy model. In this approach, the coupling constant, κ, is related to viscosity coefficient, γ , and the present dark energy density, Ω 0 DE . This coupling is bounded as. We implement recent observational data sets including a joint light-curve analysis (JLA) for SNIa, gamma ray bursts (GRBs) for most luminous astrophysical objects at high redshifts, baryon acoustic oscillations (BAO) from different surveys, Hubble parameter from HST project, Planck CMB power spectrum and lensing to constrain model free parameters. The joint analysis of JLA + GRBs + BAO + HST shows that Ω 0 DE = 0.696 ± 0.010, γ = 0.1404 ± 0.0014 and H 0 = 68.1 ± 1.3. Planck TT observation provides γ = 0.32 +0.31 −0.26 in the 68% confidence limit for the viscosity coefficient. The cosmographic distance ratio indicates that current observed data prefer to increase bulk viscosity. The competition between phantom and quintessence behavior of the viscous dark energy model can accommodate cosmological old objects reported as a sign of age crisis in the ΛCDM model. Finally, tension in the Hubble parameter is alleviated in this model. a

show abstract

“…[3] such couplings to matter were shown to be free of the Boulware-Deser (BD) ghost [12] at all scales. The cosmology with this type of coupling to matter was studied for instance in [6][7][8][13][14][15][16][17][18] (a complete list of references is beyond the scope of this note and we refer the reader to [5] for a review of many more efforts in this direction).…”

mentioning

confidence: 99%