arXiv 0812.10502008-12hep-thgr-qc

Sigma-Model Aether

Sean M. Carroll, Timothy R. Dulaney, Moira I. Gresham, Heywood Tam

备注：: 8 pages, 2 figures; fixed minor typo and changed references in v2
发表信息：: Phys.Rev.D79:065012,2009
DOI：: 10.1103/PhysRevD.79.065012

英文摘要：

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.

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