Non-Gaussianities in the Cosmological Perturbation Spectrum due to
  Primordial Anisotropy
  We investigate possible signatures of a pre-inflationary anisotropic phase in
two-point and three-point correlation functions of the curvature perturbation
for high-momentum modes which exit the horizon after isotropization. In this
momentum regime, the early time dynamics admits a WKB description and the late
time dynamics can be described in terms of a non-Bunch Davies vacuum state
which encodes the information of initial anisotropy in the background
spacetime. We compute the bi-spectrum for curvature perturbation in a canonical
single-field action with and without higher derivative operators. We show that
the bi-spectrum at late times, in either case, is enhanced for a flattened
triangle configuration as well as a squeezed triangle configuration and compute
the corresponding $f_{NL}$ parameters. The angular dependence and the
particular momentum dependence of the $f_{NL}$ parameter appear as distinctive
features of background anisotropy at early times.
