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Award ID contains: 1806871

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  1. (, Symmetry)
    null (Ed.)
    We examined the basic conservation laws for diffeomorphism symmetry in the context of spontaneous diffeomorphism and local Lorentz-symmetry breaking. The conservation laws were used as constraints on a generic series of terms in an expansion around a flat background. We found all such terms for a two-tensor coupling to cubic order in the metric and tensor field fluctuations. The results are presented in a form that can be used for phenomenological calculations. One key result is that if we preserve the underlying diffeomorphism symmetry in a spontaneous-symmetry breaking scenario, one cannot decouple the two-tensor fluctuations from the metric fluctuations at the level of the action, except in special cases of the quadratic actions. 
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  2. ; ; ; ; ; ; ; ; ; ; et al (, Physical Review D)
    null (Ed.)
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  3. ; ; (, Physical Review D)
    null (Ed.)
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  4. ; ; ; ; ; ; ; ; ; ; et al (, Physical Review Letters)
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  5. ; (, Physical Review D)
  6. ; (, Symmetry)
    We consider a model of noncommutative gravity that is based on a spacetime with broken local SO(2,3) ☆ symmetry. We show that the torsion-free version of this model is contained within the framework of the Lorentz-violating Standard-Model Extension (SME). We analyze in detail the relation between the torsion-free, quadratic limits of the broken SO(2,3) ☆ model and the Standard-Model Extension. As part of the analysis, we construct the relevant geometric quantities to quadratic order in the metric perturbation around a flat background. 
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  7. ; (, Physical Review D)
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