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We investigate possible signatures of a pre-inflationary anisotropic phase intwo-point and three-point correlation functions of the curvature perturbationfor high-momentum modes which exit the horizon after isotropization. In thismomentum regime, the early time dynamics admits a WKB description and the latetime dynamics can be described in terms of a non-Bunch Davies vacuum statewhich encodes the information of initial anisotropy in the backgroundspacetime. We compute the bi-spectrum for curvature perturbation in a canonicalsingle-field action with and without higher derivative operators. We show thatthe bi-spectrum at late times, in either case, is enhanced for a flattenedtriangle configuration as well as a squeezed triangle configuration and computethe corresponding $f_{NL}$ parameters. The angular dependence and theparticular momentum dependence of the $f_{NL}$ parameter appear as distinctivefeatures of background anisotropy at early times.

Non-Gaussianities in the Cosmological Perturbation Spectrum due to Primordial Anisotropy