Correlation of isocurvature perturbation and non-Gaussianity
  We explore the correlations between primordial non-Gaussianity and
isocurvature perturbation. We sketch the generic relation between the
bispectrum of the curvature perturbation and the cross-correlation power
spectrum in the presence of explicit couplings between the inflaton and another
light field which gives rise to isocurvature perturbation. Using a concrete
model of a Peccei-Quinn type field with generic gravitational couplings, we
illustrate explicitly how the primordial bispectrum correlates with the
cross-correlation power spectrum. Assuming the resulting fnl ~ O(1), we find
that the form of the correlation depends mostly upon the inflation model but
only weakly on the axion parameters, even though fnl itself does depend heavily
on the axion parameters.
