Primordial non-Gaussian signatures in CMB polarization
  We study the signatures of local type primordial non-Gaussianity,
parametrized by $\fnl$, of scalar perturbations in CMB polarization using the
probability distribution functions, Minkowski Functionals and Betti numbers. We
show that the lowest order non-Gaussian deviation of the PDF of the total
polarization intensity is at order $(\fnl\sigma)^2$. We calculate the
non-Gaussian deviations of Minkowski Functionals and Betti numbers from
simulated polarization maps. We find that $E$ mode polarization provides
independent and equally strong constraint on $\fnl$ as temperature
fluctuations. The non-Gaussian signal in the total polarization intensity,
however, is much weaker and has a relatively large cosmic variance and hence
may not be useful for detecting local type non-Gaussianity.
