Gauge-invariant perturbations around symmetry-reduced sectors of general relativity: applications to cosmology

  title={Gauge-invariant perturbations around symmetry-reduced sectors of general relativity: applications to cosmology},
  author={Bianca Dittrich and Johannes Tambornino},
  journal={Classical and Quantum Gravity},
  pages={4543 - 4585}
We develop a gauge-invariant canonical perturbation scheme for perturbations around symmetry-reduced sectors in generally covariant theories, such as general relativity. The central objects of investigation are gauge-invariant observables which encode the dynamics of the system. We apply this scheme to perturbations around a homogeneous and isotropic sector (cosmology) of general relativity. The background variables of this homogeneous and isotropic sector are treated fully dynamically which… 

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