Screening Modifications of Gravity through Disformally Coupled Fields
  It is shown that extensions to General Relativity, which introduce a strongly
coupled scalar field, can be viable if the interaction has a non-conformal
form. Such disformal coupling depends upon the gradients of the scalar field.
Thus, if the field is locally static and smooth, the coupling becomes invisible
in the solar system: this is the disformal screening mechanism. A cosmological
model is considered where the disformal coupling triggers the onset of
accelerated expansion after a scaling matter era, giving a good fit to a wide
range of observational data. Moreover, the interaction leaves signatures in the
formation of large-scale structure that can be used to probe such couplings.
