Higher derivatives and power spectrum in effective single field inflation

Understand

We study next-to-leading corrections to the effective action of the curvature perturbation obtained by integrating out the coupled heavy isocurvature perturbation.

• These corrections result from including higher order derivative operators, weighted by the mass scale of the heavy physics, in the effective theory expansion.
• We find that the correction terms are suppressed by the ratio of the Hubble parameter to the heavy mass scale.
• The corresponding corrections to the power spectrum of the curvature perturbation are presented for a simple illustrative example.