Observational constraints on a phenomenological $$f\left( R,\partial R\right) $$fR,∂R-model

  title={Observational constraints on a phenomenological \$\$f\left( R,\partial R\right) \$\$fR,∂R-model},
  author={Rodrigo Rocha Cuzinatto and C.A.M. de Melo and L{\'e}o G. Medeiros and P. J. Pompeia},
  journal={General Relativity and Gravitation},
This paper analyses the cosmological consequences of a modified theory of gravity whose action integral is built from a linear combination of the Ricci scalar $$R$$R and a quadratic term in the covariant derivative of $$R$$R. The resulting Friedmann equations are of the fifth-order in the Hubble function. These equations are solved numerically for a flat space section geometry and pressureless matter. The cosmological parameters of the higher-order model are fit using SN Ia data and X-ray gas… 
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