Parallel Talk | Cosmology from Home 2020
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Talk title:
A Generalized Non-Gaussian Consistency Relation for Single Field Inflation

Talk abstract:
In this talk, I will show that a perturbed inflationary spacetime, driven by a canonical single scalar field, is invariant under a special class of coordinate transformations together with a field reparametrization of the curvature perturbation in co-moving gauge. This transformation may be used to derive the squeezed limit of the 3-point correlation function of the co-moving curvature perturbations valid in the case that these do not freeze after horizon crossing. This leads to a generalized version of Maldacena’s non-Gaussian consistency relation in the sense that the bispectrum squeezed limit is completely determined by spacetime diffeomorphisms. Just as in the case of the standard consistency relation, this result may be understood as the consequence of how long-wavelength modes modulate those of shorter wavelengths. This relation allows one to derive the well-known violation of the consistency relation encountered in ultra slow-roll, where curvature perturbations grow exponentially after horizon crossing. Also, I will show that independently of whether inflation is attractor or non-attractor, the size of the observable primordial local non-Gaussianity is predicted to be fobsNL=0.

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