# Evolution of curvature perturbation in generalized gravity theories - High Energy Physics - Theory

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Abstract: Using the cosmological perturbation theory in terms of the delta-N formalism,we find the simple formulation of the evolution of the curvature perturbationin generalized gravity theories. Compared with the standard gravity theory, acrucial difference appears in the end-boundary of the inflationary stage, whichis due to the non-ideal form of the energy momentum tensor that dependsexplicitly on the curvature scalar. Recent study shows thatultraviolet-complete quantum theory of gravity may be approximated by using ageneralized gravity action. Our paper may give an important step inunderstanding the evolution of the curvature perturbation during inflation,where the energy momentum tensor may not be given by the ideal form due to thecorrections from the fundamental theory.

Author: ** Tomohiro Matsuda**

Source: https://arxiv.org/