Loop correction to the local primordial bispectrum
= Loop correction to the local primordial bispectrum
{title2=$B_{\mathrm{loop}}=O(f_{\mathrm{NL}}^3)$}
The exact <centered quadratic Gaussian transformation> has a connected three-quadratic-vertex contribution $8\alpha^3\int d^3q\,P(q)P(|\mathbf k_1-\mathbf q|)P(|\mathbf k_2+\mathbf q|)/(2\pi)^3$. It is higher order than the usual tree-level local <primordial bispectrum>. Infrared or ultraviolet regularization may be needed.