Supergravity Contributions to Inflation in models with non-minimal coupling to gravity

TL;DR

This paper analyzes how supergravity effects influence inflation models with non-minimal gravity coupling in Jordan frame supergravity, highlighting conditions under which these effects are suppressed or significant, and exploring phenomenological implications.

Contribution

It systematically studies supergravity contributions in Jordan frame inflation, identifying conditions for their suppression and impact on inflationary model building.

Findings

Supergravity corrections are suppressed if vacuum energy is from a non-inflaton F-term.

Supergravity contributions vanish if the superpotential W is zero along the inflationary trajectory.

Non-minimal coupling to gravity significantly affects inflationary dynamics and phenomenology.

Abstract

This paper provides a systematic study of supergravity contributions relevant for inflationary model building in Jordan frame supergravity. In this framework, canonical kinetic terms in the Jordan frame result in the separation of the Jordan frame scalar potential into a tree-level term and a supergravity contribution, which is potentially dangerous for sustaining inflation. We show that if the vacuum energy necessary for driving inflation originates dominantly from the F-term of an auxiliary field (i.e. not the inflaton), the supergravity corrections to the Jordan frame scalar potential are generically suppressed. Moreover, these supergravity contributions identically vanish if the superpotential $W$ vanishes along the inflationary trajectory. On the other hand, if the F-term associated with the inflaton dominates the vacuum energy, the supergravity contributions are generically comparable to the globally supersymmetric contributions. In addition, the non-minimal coupling to gravity inherent to Jordan frame supergravity significantly impacts the inflationary model depending on the size and sign of this coupling. We discuss the phenomenology of some representative inflationary models, and point out the relation to the recently much discussed cosmological `attractor' models.