Disformal vectors and anisotropies on a warped brane

Abstract

The Maxwell action is conformally invariant and classically ignorant of conformally flat metrics. However, if the vector lives in a disformal metric--- as it does if residing upon a moving brane---this is no longer true. The disformal coupling is then mediated by a Dirac-Born-Infeld scalar field. Here a systematic dynamical system analysis is developed for anisotropic Bianchi I cosmology with a massive disformally coupled vector field. Several new fixed points are found, including anisotropic scaling solutions. The presented formalism here presented can be conveniently applied to general scenarios with or without extra dimensional motivations. This is illustrated here by performing a complete analysis with simple assumption that both the potentials and the warp factor for the brane are (nearly) exponential. In that case, the anisotropic fixed points are either not attractors, do not describe accelerating expansion or else they feature too large anisotropies to be compatible with observations. Nonetheless, viable classes of models exist where isotropy is retained due to rapid oscillations of the vector field, thus providing a possible realisation of disformally interacting massive dark matter.

13 pages -- 4 numerical examples, v2 corrects a mistake in the equations; the conclusions are essentially unchanged

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Cited by in corpus (6)

• Constraints on a Bianchi type I spacetime extension of the standard $\Lambda$CDM model
• Testing spatial curvature and anisotropic expansion on top of the $\Lambda$CDM model
• Screening anisotropy via energy-momentum squared gravity: $\Lambda$CDM model with hidden anisotropy
• Conformally and Disformally Coupled Vector field Models of Dark Energy
• Anisotropic Scalar Field Dark Energy with a Disformally Coupled Yang-Mills Field
• Non-Gaussianity in multi-sound-speed disformally coupled inflation