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 fNL sourced by a specific interaction term. We show that the running of fNL can be substantially larger than what dictated by the slow-roll parameters.
Highlights
We here solve the equation of motion for the second-order effective Lagrangian derived in [23] at leading order in slow-roll: L2 = a3
The procedure according to which the Lagrangian was obtained is outlined in [23] and allows for a very general expression for inflation driven by a single scalar degree of freedom
In this work we employed the tools of effective field theory to analyze a very general theory of inflation driven by a single scalar degree of freedom
Summary
For β0 = 0, α0 ∼ 1 one recovers k2τ∗2 ∼ 1 at the horizon At this stage we can perform a consistency check and show how one can generalize the argument, initially borrowed from DBI-like inflationary models, that in comparing terms at the same order in perturbations and with the same overall number of derivatives, the ones with the most space derivatives are dominating in the cs ≪ 1 limit. The generalization of this argument consists in restricting the parameters space to the α0 ≪ 1 and β0 ≪ 1 region. Since the main contributions to correlators comes from the horizon-crossing region, this shows that, for (α0, β0) ≪ 1 we can still identify leading terms in the Lagrangian according to the standard procedure
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