Dark energy and dark matter from nonlocal ghost-free gravity theory
  We suggest a class of generally covariant ghost-free nonlocal gravity models generating de Sitter or Anti-de Sitter background with an arbitrary value of the effective cosmological constant and featuring a mechanism of dark matter simulation. These models interpolate between the general relativistic phase on a flat spacetime background and their strongly coupled infrared (Anti)-de Sitter phase with two propagating massless graviton modes. 
A. O. Barvinsky
hep-th astro-ph.CO gr-qc