Cosmology with a dynamically screened scalar interaction in the dark   sector
  Motivated in part by string theory, we consider a modification of the LambdaCDM cosmological model in which the dark matter has a long-range scalar force screened by light particles. Scalar forces can have interesting effects on structure formation: the main example presented here is the expulsion of dark matter halos from low density regions, or voids, in the galaxy distribution. 
Steven S. Gubser and P.J.E. Peebles