Tilt and Running of Cosmological Observables in Generalized Single-Field Inflation

TL;DR

This paper uses effective field theory to analyze how curvature-related operators influence inflationary observables, especially their scale dependence, and finds that non-Gaussianity running can be significantly enhanced beyond slow-roll predictions.

Contribution

It provides a detailed calculation of the running of inflationary observables, including the power spectrum and non-Gaussianity, in a very general single-field inflation framework.

Findings

The power spectrum tilt and running are derived at next-to-leading order.

The non-Gaussianity amplitude f_{NL} can have a running much larger than slow-roll estimates.

Curvature-generated operators significantly impact the scale dependence of inflationary observables.

Abstract

Employing an effective field theory approach to inflationary perturbations, we analyze in detail the effect of curvature-generated Lagrangian operators on various observables, focusing on their running with scales. At quadratic order, we solve the equation of motion at next-to-leading leading order in a generalized slow-roll approximation for a very general theory of single-field inflation. We derive the resulting power spectrum, its tilt and running. We then focus on the contribution to the primordial non-Gaussianity amplitude f_{NL} sourced by a specific interaction term. We show that the running of f_{NL} can be substantially larger than what dictated by the slow-roll parameters.