Large Field Inflation and Double $\alpha$-Attractors

TL;DR

This paper explores a class of supergravity-based inflationary models characterized by a parameter alpha, showing how their predictions interpolate between plateau and quadratic inflation, aligning with observations from Planck and BICEP2.

Contribution

It introduces a broad class of alpha-attractor inflation models that unify different inflationary predictions within a single framework based on supergravity.

Findings

Models interpolate between plateau and quadratic inflation predictions.

Predictions match observational data from Planck and BICEP2.

Universal behavior explained by stretching of the moduli space.

Abstract

We consider a broad class of inflationary models that arise naturally in supergravity. They are defined in terms of a parameter $\alpha$ that determines the curvature and cutoff of these models. As a function of this parameter, we exhibit that the inflationary predictions generically interpolate between two attractor points. At small cutoff $\alpha$, the resulting inflationary model is of plateau-type with $n_s = 1 - 2 / N$ and $r = 12 \alpha / N^2$. For $\alpha = 1$, these predictions coincide with predictions of the Starobinsky model and Higgs inflation. In contrast, for large cutoff $\alpha$, the theory asymptotes to quadratic inflation, with $n_s = 1 - 2 / N$, $r = 8 / N$. Both universal predictions can be attributed to a stretching of the moduli space. For intermediate values of $\alpha$, the predictions interpolate between these two critical points, thus covering the sweet spots of both Planck and BICEP2.