Non-Gaussianity in Nonminimally Coupled Scalar Field Theory

Abstract

We consider the non-Gaussianity of the nonlinear density perturbations in a single-field inflationary model when a scalar field couples nonminimally with gravity. Gravity theories with a nonminimal coupling can be transformed into the Einstein gravity with canonical kinetic terms by using a suitable conformal transformation. We find that a nonlinear generalization of the gauge invariant quantity ${\zeta }_i$ is invariant under the conformal transformation. With the help of this conformal invariant property, we calculate the non-Gaussianity, which is characterized by a nonlinear parameter $f_{NL}$, in nonminimal coupled scalar field theory.

4pages, talk at the 9th Italian-Korean Symposium on Relativistic Astrophysics, Seoul and Mt. Kumkang, Korea,19-24 July 2005; corrected typos

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• Conformal invariance of curvature perturbation
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• Large non-Gaussianity in non-minimal inflation
• Non-minimally coupled hybrid inflation
• Effects of Variable Newton Constant During Inflation