Decoherence of Homogeneous and Isotropic Metrics in the Presence of   Massive Vector Fields
  Retrieval of classical behaviour in quantum cosmology is usually discussed in the framework of minisuperspace models in the presence of scalar fields together with the inhomogeneous modes either of the gravitational or of the scalar fields. In this work we propose alternatively a model where the scalar field is replaced by a massive vector field with global $U(1)$ or SO(3) symmetries. 
O. Bertolami and P.V. Moniz