On Non-Canonical Kinetic Terms and the Tilt of the Power Spectrum

TL;DR

This paper explores how non-canonical kinetic terms in two-field inflation models can produce a red tilt in the power spectrum, with a simple model demonstrating the effect and its implications for inflationary scales.

Contribution

It introduces a simple two-field inflation model with non-canonical kinetic terms that can generate a red tilt in the power spectrum from interactions between perturbations.

Findings

Non-canonical kinetic terms can induce a red tilt in the power spectrum.

Numerical analysis supports the model's predictions.

Potential decoupling of inflation scale from fluctuation amplitude.

Abstract

We argue that in models of inflation with two scalar fields and non-canonical kinetic terms there is a possibility of obtaining a red tilt of the power spectrum of curvature perturbations from noncanonicality-induced interactions between the curvature and isocurvature perturbations. We describe an extremely simple model realizing this idea, study numerically its predictions for the perturbations and discuss applications in realistic scenarios of inflation. We discuss to what extent in this model the scale of the inflationary potential can be decoupled from the amplitude of the density fluctuations.