F-term inflation in Superstring Theories

TL;DR

This paper explores how string-based F-term inflation models can naturally achieve small slow-roll parameters by utilizing orbifold constructions with moduli fields, enabling successful inflation despite supergravity corrections.

Contribution

It introduces a mechanism in string-inspired F-term inflation models that maintains flat potentials by involving moduli fields, demonstrating successful inflation with gaugino condensation.

Findings

Small eta achieved in string-based F-term inflation models

Hybrid inflation models based on orbifold constructions are viable

Gaugino condensation can generate suitable inflaton potentials

Abstract

A supersymmetric inflationary stage dominated by an $F$-term has the problem that the flatness of the potential is spoiled by supergravity corrections, that is the slow-roll parameter $\eta$ gets contributions of order unity. We show that in $F$-term inflationary models based on strings there is natural way of obtaining small values of $\eta$. This happens in models of hybrid inflation based on orbifold constructions, in which a modulus $T$ field is responsible for the large value of the potential during inflation, and a second field $\phi$ with appropriate modular weight is responsible for the roll-over. We illustrate the mechanism with a model in which the inflaton potential is provided by gaugino condensation, leading to succesful inflation.