Cosmic acceleration and the helicity-0 graviton

By Claudia de Rham, G. Gabadadze, Lavinia Heisenberg, D. Pirtskhalava. 2010

193 citations recorded by the source corpus.

We explore cosmology in the decoupling limit of a nonlinear covariant extension of Fierz-Pauli massive gravity obtained recently in arXiv:1007.0443. In this limit the theory is a scalar-tensor model of a unique form defined by symmetries. We find that it admits a self-accelerated solution, with the Hubble parameter set by the graviton mass. The negative pressure causing the acceleration is due to a condensate of the helicity-0 component of the massive graviton, and the background evolution, in the approximation used, is indistinguishable from the {Lambda}CDM model. Fluctuations about the self-accelerated background are stable for a certain range of parameters involved. Most surprisingly, the fluctuation of the helicity-0 field above its background decouples from an arbitrary source in the linearized theory. We also show how massive gravity can remarkably screen an arbitrarily large cosmological constant in the decoupling limit, while evading issues with ghosts. The obtained static solution is stable against small perturbations, suggesting that the degravitation of the vacuum energy is possible in the full theory. Interestingly, however, this mechanism postpones the Vainshtein effect to shorter distance scales. Hence, fifth force measurements severely constrain the value of the cosmological constant that can be neutralized, making this scheme phenomenologically not viablemore » for solving the old cosmological constant problem. We briefly speculate on a possible way out of this issue.« less

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/5290a6bf89edc4dc9cff6463190ad445136afda4

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Citations in the corpus

On couplings to matter in massive (bi-)gravity (2014, background): “ which strongly suggests that highly anisotropic solutions of the theory would excite the BD ghost. In massive gravity, the study of cosmological solutions has been notoriously challenging (see Refs. [44,52{76]), with more success in its quasi-dilaton and bi-gravity extensions (see Refs. [77{82] and”
Cosmological solutions with massive gravitons in the bigravity theory (2011, background): “Recently it was claimed in the literature that the RTG theory does not actually admit homogeneous and isotropic cosmological solutions [12] (apart from those obtained in the decoupling limit [13]).”
Modified Gravity and Cosmology (2011, background): “Self-accelerating and self-tuning cosmologies were studied de Rham and Gabadadze’s theory in [384], whilst spherically symmetric solutions have also been considered recently [738, 739, 297].”
Theoretical Aspects of Massive Gravity (2011, background): “Properties of this lagrangian, including its cosmological solutions, degravitation effects and phenomenology are studied in [144].”
On non-linear actions for massive gravity (2011, background): “ability to cancel a � in this way generalizes the mechanism of screening of cosmological constant, discussed for a flat spacetime in [12, 22, 29 , 33], to any background sourced by any Tµ�.”
Cosmology and Fundamental Physics with the Euclid Satellite (2012, background): “The helicity-0 degree of freedom of massive gravity forms a condensate whose energy density sources self-acceleration [393].”
Helicity decomposition of ghost-free massive gravity (2011, background): “(In the decoupling limit, full diffeomorphism invariance always reduces to the linearized diffeomorphism invariance, but this is true only in the decoupling limit [5, 17]).”
Horndeski theory and beyond: a review (2019, background): “This mixing cannot be eliminated by a field redefinition [225].”
Beyond the Cosmological Standard Model (2014, unknown): “In order for this to describe a de Sitter solution (with H > 0) and for scalar and tensor perturbations about this solution to be stable, the parameters a2 and a3 must satisfy [259, 635] a2 < 0 ; − 2a(2)2 3 < a3 < − a(2)2 2 .”