Disappearing cosmological constant in f(R) gravity

@article{Starobinsky2007DisappearingCC,
  title={Disappearing cosmological constant in f(R) gravity},
  author={Alexei A. Starobinsky},
  journal={JETP Letters},
  year={2007},
  volume={86},
  pages={157-163}
}
For higher-derivative f(R) gravity, where R is the Ricci scalar, a class of models is proposed, which produce viable cosmology different from the ACDM at recent times and satisfy cosmological, Solar System, and laboratory tests. These models have both flat and de Sitter spacetimes as particular solutions in the absence of matter. Thus, a cosmological constant is zero in a flat spacetime, but appears effectively in a curved one for sufficiently large R. A “smoking gun” for these models would be… 

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