The Hyperbolic Geometry of Cosmological Attractors

TL;DR

This paper explores the hyperbolic geometry underlying cosmological alpha-attractors, introducing a new Kahler potential frame that preserves shift symmetry and stabilizes inflationary models within supergravity.

Contribution

It presents a novel Kahler potential formulation that maintains shift symmetry and incorporates higher-order curvature deformations for stable inflation in supergravity models.

Findings

The new Kahler potential preserves inflaton shift symmetry.

Higher-order curvature terms stabilize orthogonal directions.

Framework successfully stabilizes single superfield alpha-attractors.

Abstract

Cosmological alpha-attractors give a natural explanation for the spectral index n_s of inflation as measured by Planck while predicting a range for the tensor-to-scalar ratio r, consistent with all observations, to be measured more precisely in future detection of gravity waves. Their embedding into supergravity exploits the hyperbolic geometry of the Poincare disk or half-plane. These geometries are isometric under Mobius transformations, which include the shift symmetry of the inflaton field. We introduce a new Kahler potential frame that explicitly preserves this symmetry, enabling the inflaton to be light. Moreover, we include higher-order curvature deformations, which can stabilize a direction orthogonal to the inflationary trajectory. We illustrate this new framework by stabilizing the single superfield alpha-attractors.