A self-consistent effective field theory of modified gravity has recently been proposed with spontaneous breaking of local Lorentz invariance. The symmetry is broken by a vector field with the wrong-sign mass term and it has been shown to have additional graviton modes and modified dispersion relations. In this paper we study the evolution of a homogeneous and isotropic universe in the presence of such a vector field with a minimum lying along the timelike direction. A plethora of different regimes is identified, such as accelerated expansion, loitering, collapse, and tracking.

• Received 13 November 2006

DOI:https://doi.org/10.1103/PhysRevD.75.044014