Disformal Transformations, Veiled General Relativity and Mimetic Gravity
  In this Note we show that Einstein's equations for gravity are generically invariant under 'disformations'. We also show that the particular subclass when this is not true yields the equations of motion of 'Mimetic Gravity'. Finally we give the 'mimetic' generalization of the Schwarzschild solution. 
Nathalie Deruelle and Josephine Rua
gr-qc hep-th