Zachary Kenton (Queen Mary University of London, United Kingdom)
Soft limits of correlation functions of the primordial curvature perturbation provide a unique opportunity to confront theoretically clean results against observations of non-Gaussianity. In this work we calculate the squeezed limit of the bispectrum of the curvature perturbation produced by multifield inflation, which allows for a very large hierarchy of scales. This is achieved by taking different exit times for different modes, as required in the squeezed limit. We allow the field perturbations to evolve between these exit times and then apply the delta-N formalism from the time the last mode exits to find the bispectrum and other observables in the squeezed limit. This allows one to investigate the highly squeezed limit, and we find significant differences to previous results which were valid only for a mild squeezing. This work was produced in collaboration with David Mulryne, and will appear on the arxiv shortly.