Key points are not available for this paper at this time.
Motivated in part by string theory, we consider a modification of the 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.
Gubser et al. (Mon,) studied this question.