Cosmology of a Scalar Field Coupled to Matter and an Isotropy-Violating
  Maxwell Field
  Motivated by the couplings of the dilaton in four-dimensional effective
actions, we investigate the cosmological consequences of a scalar field coupled
both to matter and a Maxwell-type vector field. The vector field has a
background isotropy-violating component. New anisotropic scaling solutions
which can be responsible for the matter and dark energy dominated epochs are
identified and explored. For a large parameter region the universe expands
almost isotropically. Using that the CMB quadrupole is extremely sensitive to
shear, we constrain the ratio of the matter coupling to the vector coupling to
be less than 10^(-5). Moreover, we identify a large parameter region,
corresponding to a strong vector coupling regime, yielding exciting and viable
cosmologies close to the LCDM limit.
