Anisotropic stress and stability in modified gravity models

@article{Saltas2010AnisotropicSA,
  title={Anisotropic stress and stability in modified gravity models},
  author={Ippocratis D. Saltas and Martin Kunz},
  journal={Physical Review D},
  year={2010},
  volume={83},
  pages={064042}
}
The existence of anisotropic stress of a purely geometrical origin seems to be a characteristic of higher order gravity models, and has been suggested as a probe to test these models observationally, for example, in weak lensing experiments. In this paper, we seek to find a class of higher order gravity models of f(R,G) type that would give us a zero anisotropic stress and study the consequences for the viability of the actual model. For the special case of a de Sitter background, we identify a… 

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