2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/124539We 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 $ζ_i$ 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 typosAstrophysicsGeneral Relativity and Quantum CosmologyHigh Energy Physics - Theorytext