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Nonlinear Evolutions and Non-Gaussianity in Generalized Gravity

Seoktae Koh·Sang Pyo Kim·Doo Jong Song
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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.

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Seoktae Koh, Sang Pyo Kim, Doo Jong Song. 2005-01-26. Nonlinear Evolutions and Non-Gaussianity in Generalized Gravity. https://doi.org/10.1103/physrevd.71.123511

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