The consistency condition for the three-point function in dissipative single-clock inflation

TL;DR

This work extends the inflationary consistency condition to dissipative, multi-field single-clock models using the EFT of inflation with dissipation. It demonstrates, to leading non-trivial order in generalized slow-roll parameters and gravity mixing, that the squeezed limit of ⟨ζ ζ ζ⟩ obeys f_NL^sq = -(5/12)(n_s−1) when a preferred clock is present, with the first corrections scaling as (k_L/k_S)^2. The analysis relies on a local noise/response framework for the dissipative sector and shows that long-wavelength modes act as coordinate rescalings outside the horizon. These results constrain broad classes of inflationary scenarios (e.g., warm and trapped inflation) and inform upcoming observations from Planck and large-scale structure surveys.

Abstract

We generalize the consistency condition for the three-point function in single field inflation to the case of dissipative, multi-field, single-clock models. We use the recently introduced extension of the effective field theory of inflation that accounts for dissipative effects, to provide an explicit proof to leading (non-trivial) order in the generalized slow roll parameters and mixing with gravity scales. Our results illustrate the conditions necessary for the validity of the consistency relation in situations with many degrees of freedom relevant during inflation, namely that there is a preferred clock. Departures from this condition in forthcoming experiments would rule out not only single field but also a large class of multi-field models.