Cosmological perturbations from vector inflation
  We analyze the behavior of linear perturbations in vector inflation. In
contrast to the scalar field inflation, the linearized theory with vector
fields contains couplings between scalar, vector and tensor modes. The
perturbations decouple only in the ultraviolet limit, which allows us to carry
out the canonical quantization. Superhorizon perturbations can be approximately
analyzed due to suppressed mixing between different modes in the small fields
models. We find that the vector perturbations of the metric decay
exponentially, but the scalar and tensor modes could remain weakly coupled
throughout the evolution. As a result, the vector inflation can produce
significant correlations of the scalar and tensor modes in the CMB. For the
realistic models the effect is rather small, but not negligible.
