A MODIFIED MODEL OF NONLOCALLY CORRECTED GRAVITY: COSMOLOGY AND THE NEWTONIAN LIMIT

A modified form of nonlocally corrected theory of gravity is investigated in the context of cosmology and the Newtonian limit. This form of nonlocal correction to classic Einstein-Hilbert action can be locally represented by a triple-scalar-tensor theory in which one of the scalar degrees of freedom is phantom-like and the other two are quintessence-like. We show that there exists a stable de Sitter solution for the cosmological dynamics if a suitable form of potential function V(phi) (orequivalently, f(R)) is selected. However, no matter what a potential function is selected, there is always an early time repeller solution corresponding to a radiation dominated universe. Besides, the equations for linear scalar perturbations are presented and it is shown that the form of potential function V(phi) is stringently constrained by the solar system test, although the post Newtonian parameter gamma is not directly affected by this function.