Rastall's Cosmology and its Observational Constraints
  The Rastall's theory is a modification of General Relativity touching one of the cornestone of gravity theory: the conservation laws. In Rastall's theory, the energy-momentum tensor is not conserved anymore, depending now on the gradient of the Ricci curvature. In this sense, this theory can be seen as a classical implementation of quantum effects in a curved background space-time. We exploit this structure in order to reproduce some results of an effective theory of quantum loop cosmology. Later, we propose a model for the dark sector of the universe. In this case, the corresponding $\Lambda$CDM model appears as the only model consistent with observational data. 
J.C. Fabris, O.F. Piattella, D.C. Rodrigues, M.H. Daouda
gr-qc astro-ph.CO hep-th