  Predicting signatures of string theory on cosmological observables is not
sufficient. Often the observable effects string theory may impact upon the
cosmological arena may equally be predicted by features of inflationary
physics. The question: what observable signatures are unique to new physics, is
thus of crucial importance for claiming evidence for the theory. Here we
discuss recent progress in addressing the above question. The evidence relies
on identifying discrepancies between the source terms that give rise to large
scale structure (LSS) and CMB, by cross-correlating the weak lensing potential
maps LSS with the CMB spectra.
