On the Starobinsky Model of Inflation from Supergravity

TL;DR

This paper explores how the Starobinsky inflation model can be derived from different formulations of supergravity, highlighting its equivalence to no-scale models and vector multiplet frameworks, and discusses potential threats from higher-order corrections.

Contribution

It demonstrates the origin of the Starobinsky model within both old-minimal and new-minimal supergravity formulations, revealing new perspectives on its structure and stability.

Findings

Starobinsky model is equivalent to a no-scale F-term model in old-minimal supergravity.

In new-minimal supergravity, it corresponds to supergravity coupled to a massive vector multiplet.

Higher-order corrections can threaten the flatness of the inflaton potential.

Abstract

We discuss how the higher-derivative Starobinsky model of inflation originates from N=1 supergravity. It is known that, in the old-minimal supergravity description written by employing a chiral compensator in the superconformal framework, the Starobinsky model is equivalent to a no-scale model with F-term potential. We show that the Starobinsky model can also be originated within the so-called new-minimal supergravity, where a linear compensator superfield is employed. In this formulation, the Starobinsky model is equivalent to standard supergravity coupled to a massive vector multiplet whose lowest scalar component plays the role of the inflaton and the vacuum energy is provided by a D-term potential. We also point out that higher-order corrections to the supergravity Lagrangian represent a threat to the Starobinsky model as they can destroy the flatness of the inflaton potential in its scalar field equivalent description.