Primordial bispectrum
= Primordial bispectrum
{title2=$B(k_1,k_2,k_3)$}
{wiki=Bispectrum}
Statistical homogeneity defines the primordial bispectrum by
$$
\langle\phi_{\mathbf k_1}\phi_{\mathbf k_2}\phi_{\mathbf k_3}\rangle
=(2\pi)^3\delta^{(3)}(\mathbf k_1+\mathbf k_2+\mathbf k_3)
B(k_1,k_2,k_3).
$$