Sigma-Model Aether
Jan, 2009
8 pages
Published in:
- Phys.Rev.D 79 (2009) 065012
e-Print:
- 0812.1050 [hep-th]
Report number:
- CALT-68-2713
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Citations per year
Abstract: (arXiv)
Theories of low-energy Lorentz violation by a fixed-norm 'aether' vector field with two-derivative kinetic terms have a globally bounded Hamiltonian and are perturbatively stable only if the vector is timelike and the kinetic term in the action takes the form of a sigma model. Here we investigate the phenomenological properties of this theory. We first consider the propagation of modes in the presence of gravity, and show that there is a unique choice of curvature coupling that leads to a theory without superluminal modes. Experimental constraints on this theory come from a number of sources, and we examine bounds in a two-dimensional parameter space. We then consider the cosmological evolution of the aether, arguing that the vector will naturally evolve to be orthogonal to constant-density hypersurfaces in a Friedmann-Robertson-Walker cosmology. Finally, we examine cosmological evolution in the presence of an extra compact dimension of space, concluding that a vector can maintain a constant projection along the extra dimension in an expanding universe only when the expansion is exponential.- 04.40.Nr
- 11.30.Cp
- ether
- field theory: vector
- curvature: coupling
- violation: Lorentz
- sigma model
- higher-dimensional
- superluminal
- stability
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