Nonlinear Evolutions and Non-Gaussianity in Generalized Gravity

Abstract

We use the Hamilton-Jacobi theory to study the nonlinear evolutions of inhomogeneous spacetimes during inflation in generalized gravity. We find the exact solutions to the lowest order Hamilton-Jacobi equation for special scalar potentials and introduce an approximation method for general potentials. The conserved quantity invariant under a change of timelike hypersurfaces proves useful in dealing with gravitational perturbations. In the long-wavelength approximation, we find a conserved quantity related to the new canonical variable that makes the Hamiltonian density vanish, and calculate the non-Gaussianity in generalized gravity. The slow-roll inflation models with a single scalar field in generalized gravity predict too small non-Gaussianity to be detected by future CMB experiments.

17 pages, 2 figures; added references

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Cited by in corpus (6)

• Nongaussianity from Tachyonic Preheating in Hybrid Inflation
• Large Nongaussianity from Nonlocal Inflation
• Predictions for Nongaussianity from Nonlocal Inflation
• The Conformal Transformation in General Single Field Inflation with Non-Minimal Coupling
• Uniqueness of the gauge invariant action for cosmological perturbations
• Inflationary Solutions in Nonminimally Coupled Scalar Field Theory