Curvature bispectrum from a zeta zeta-prime-squared interaction
= Curvature bispectrum from a zeta zeta-prime-squared interaction
{title2=$B_{\zeta\zeta\prime^2}$}
For $H_{\mathrm{int}}=-M_{\mathrm{Pl}}^2\int d^3x\,a^3\epsilon^2\zeta\dot\zeta^2$ and the standard Gaussian de Sitter modes, the tree <in-in formalism> gives $B=H^4\sum_{\mathrm{cyc}}k_2^2k_3^2(K^{-1}+k_1K^{-2})/[16\epsilon M_{\mathrm{Pl}}^4(k_1k_2k_3)^3]$, where $K=\sum_i k_i$. The result includes six connected <Wick contractions> and a vacuum contour.