 Local-type primordial non-Gaussianity

A local quadratic departure from a Gaussian random field isThe subtraction removes the homogeneous mean. At leading order, Wick theorem gives the primordial bispectrum $B_{\phi }=2f_{\mathrm{NL}}[P_{\phi }(k_1)P_{\phi }(k_2)+\text{cyclic terms}]$. The numerical convention depends on which potential or comoving curvature perturbation is used.