Slow-roll amplitude of the squeezed zeta zeta-prime-squared bispectrum
= Slow-roll amplitude of the squeezed zeta zeta-prime-squared bispectrum
{title2=$f_{\mathrm{NL}}^{\mathrm{effective}}=5\epsilon/24$}
The undifferentiated soft-leg permutation gives $B(q,k,k)\simeq(\epsilon/2)P(q)P(k)$ as $q/k\to0$. It retains a squeezed $q^{-3}$ enhancement, but corresponds to local amplitude $f_{\mathrm{NL}}^{\mathrm{effective}}=5\epsilon/24$. Soft momentum placed only at derivative slots would miss this dominant term.