N. Bartolo, E. Komatsu, S. Matarrese, и A. Riotto. (2004)cite arxiv:astro-ph/0406398Comment: LaTeX file: 218 pages, 19 figures. Replaced to match the accepted version in Physics Reports. A high-resolution version of Fig. 2 can be downloaded from: http://www.pd.infn.it/~liguori/Non_Gaussianity/.