Massive gravity, the elasticity of space-time and perturbations in the dark sector

Jan, 2013
8 pages
Published in:
  • Phys.Rev.D 88 (2013) 8, 084004
  • Published: Oct 3, 2013
e-Print:

Citations per year

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Abstract: (APS)
We consider a class of phenomenological modified gravity models where the terms added to the standard Einstein-Hilbert Lagrangian are just a function of the metric only. For linearized perturbations around an isotropic space-time, this class of models is entirely specified by a rank-4 tensor that encodes possibly time-dependent masses for the gravitons. This tensor has the same symmetries as an elasticity tensor, suggesting an interpretation of massive gravity as an effective rigidity of space-time. If we choose a form for this tensor that is compatible with the symmetries of Friedmann-Robertson-Walker and enforce full reparametrization invariance, then the only theory possible is a cosmological constant. However, in the case where the theory is only time translation invariant, the ghost-free massive gravity theory is equivalent to the elastic dark energy scenario with the extra Lorentz violating vector giving rise to 2 transverse and 1 longitudinal degrees of freedom, whereas when one demands spatial translation invariance one is left with a theory where the entropy perturbation is not gauge invariant.
Note:
  • 10 pages
  • 04.50.Kd
  • 14.70.Kv
  • 98.80.Es
  • gravitation: massive
  • gravitation: model
  • field theory: scalar
  • mass: time dependence
  • perturbation: linear
  • violation: Lorentz
  • invariance: Lorentz