Sigma-Model Aether

Abstract

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.

8 pages, 2 figures; fixed minor typo and changed references in v2

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• Einstein-Aether Waves
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• Instabilities in the Aether
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Cited by in corpus (17)

• Scalar-Scalar, Scalar-Tensor, and Tensor-Tensor Correlators from Anisotropic Inflation
• Ghost instabilities of cosmological models with vector fields nonminimally coupled to the curvature
• On the aether-like Lorentz-breaking actions
• Inflation and dark energy from three-forms
• Bare and Induced Lorentz and CPT Invariance Violations in QED
• Instabilities in the Aether
• Cosmological evolution in vector-tensor theories of gravity
• Time-delay and Doppler tests of the Lorentz symmetry of gravity
• Feynman propagator for the nonbirefringent CPT-even electrodynamics of the Standard Model Extension
• Vector models of gravitational Lorentz symmetry breaking
• Cosmological models with Lagrange Multiplier Field
• A Static Spherically Symmetric Solution of the Einstein-aether Theory
• Forbidden Landscape from Holography
• Observational Constraints on Local Lorentz Invariance
• K-essence Explains a Lorentz Violation Experiment
• The radiatively corrected Kaluza-Klein masses in aether compactification
• Introduction of the generalized Lorenz gauge condition into the vector-tensor theory