Mimetic Tensor-Vector-Scalar Cosmology: Unified Dark Energy, Dark Matter
  and Stiff Matter
  Phenomenological implications of the Mimetic Tensor-Vector-Scalar theory
(MiTeVeS) are studied. The theory is an extension of the vector field model of
mimetic dark matter, where a scalar field is also incorporated, and it is known
to be free from ghost instability. In the absence of interactions between the
scalar field and the vector field, the obtained cosmological solution
corresponds to the General theory of Relativity (GR) with a minimally-coupled
scalar field. However, including an interaction term between the scalar field
and the vector field yields interesting dynamics. There is a shift symmetry for
the scalar field with a flat potential, and the conserved Noether current,
which is associated with the symmetry, behaves as a dark matter component.
Consequently, the solution contains a cosmological constant, dark matter and a
stiff matter fluid. Breaking the shift symmetry with a non-flat potential gives
a natural interaction between dark energy and dark matter.
