Volume modulus inflation and a low scale of SUSY breaking

TL;DR

This paper explores how to achieve slow-roll inflation with a low scale of supersymmetry breaking in string modulus models, emphasizing the importance of specific corrections to the Kahler potential and superpotential design.

Contribution

It demonstrates that a compatible model with low-scale SUSY breaking and inflation can be constructed using a triple gaugino condensation superpotential and string-corrected Kahler potential.

Findings

Low-scale SUSY breaking compatible with inflation is possible with specific Kahler and superpotential corrections.

The popular racetrack superpotential is unsuitable for this purpose.

A new model with triple gaugino condensation is proposed and analyzed.

Abstract

The relation between the Hubble constant and the scale of supersymmetry breaking is investigated in models of inflation dominated by a string modulus. Usually in this kind of models the gravitino mass is of the same order of magnitude as the Hubble constant which is not desirable from the phenomenological point of view. It is shown that slow-roll saddle point inflation may be compatible with a low scale of supersymmetry breaking only if some corrections to the lowest order Kahler potential are taken into account. However, choosing an appropriate Kahler potential is not enough. There are also conditions for the superpotential, and e.g. the popular racetrack superpotential turns out to be not suitable. A model is proposed in which slow-roll inflation and a light gravitino are compatible. It is based on a superpotential with a triple gaugino condensation and the Kahler potential with the leading string corrections. The problem of fine tuning and experimental constraints are discussed for that model.