Abstract
We study supersymmetric extension of the Einstein-aether gravitational model where local Lorentz invariance is broken down to the subgroup of spatial rotations by a vacuum expectation value of a timelike vector field called aether. Embedding aether into a chiral vector superfield, we construct the most general action which describes dynamics of linear perturbations around the Lorentz-violating vacuum and is invariant under the linearized supergravity transformations. The analysis is performed both in the off-shell non-minimal superfield formulation of supergravity and in the “on-shell” approach invoking only physical component fields. The resulting model contains a single free coupling, in addition to the standard supergravity parameters. The spectrum of physical excitations features an enhanced on-shell gravity multiplet comprising four states with helicities 2, 3/2, 3/2 and 1 propagating with superluminal velocity. The remaining excitations propagate with the speed of light. We outline the observational constraints on the model following from its low-energy phenomenology.
Highlights
Introduction and summaryThe possibility to modify the laws of gravity has been the subject of an intensive theoretical research during recent decades [1,2,3,4,5,6,7,8], see [9] for review
We study supersymmetric extension of the Einstein-aether gravitational model where local Lorentz invariance is broken down to the subgroup of spatial rotations by a vacuum expectation value of a timelike vector field called aether
Our construction is based on embedding aether as the lowest component into a chiral vector superfield which ensures that aether vacuum expectation value (VEV) does not break SUSY
Summary
The possibility to modify the laws of gravity has been the subject of an intensive theoretical research during recent decades [1,2,3,4,5,6,7,8], see [9] for review. We find that local SUSY highly constrains the aether sector leaving only a single free parameter that is identified with c1 in the low-energy theory, whereas the parameters c2 and c3 are forced to vanish This path directly leads us to the quadratic action for perturbations in components, which we use to analyze the dispersion relations of various physical modes. We find that the velocity of gravitons necessarily exceeds the speed of light, thereby manifesting violation of the Lorentz invariance in the low-energy theory This is in contrast with the Standard Model matter and gauge fields which are protected by SUSY from Lorentz symmetry violation at low energies [31, 32].
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