Super-horizon evolution and the fate of f_NL

Local form primordial non-Gaussianity is a powerful probe of the number of effective degrees of freedom during the inflationary epoch. In this paper, we have described the recent work, which attempts to further narrow down the set of multi-field models that can result in large local non-Gaussianities. This is done by imposing the constraint that any iso-curvature produced by multi-field inflation be eliminated before the end of the inflationary epoch. In the restricted class of models studied, where non-Gaussianity is produced by a sharp turn in field space and eliminated by a short phase of single field inflation, it is found that adiabaticity and a large local f_NL are incompatible