Gravity waves and the LHC: Towards high-scale inflation with low-energy SUSY

TL;DR

This paper proposes string-inspired supergravity models that dynamically generate a hierarchy between the inflationary Hubble scale and the gravitino mass, addressing the challenge of reconciling high-scale inflation with low-energy supersymmetry.

Contribution

It introduces a class of supergravity models where the superpotential expectation value relaxes during inflation, enabling small gravitino masses despite high inflationary scales.

Findings

Achieves small m_{3/2} to H ratios in toy models

Demonstrates superpotential relaxation during inflation

Models do not fit cosmological data for m_{3/2} < TeV

Abstract

It has been argued that rather generic features of string-inspired inflationary theories with low-energy supersymmetry (SUSY) make it difficult to achieve inflation with a Hubble scale H > m_{3/2}, where m_{3/2} is the gravitino mass in the SUSY-breaking vacuum state. We present a class of string-inspired supergravity realizations of chaotic inflation where a simple, dynamical mechanism yields hierarchically small scales of post-inflationary supersymmetry breaking. Within these toy models we can easily achieve small ratios between m_{3/2} and the Hubble scale of inflation. This is possible because the expectation value of the superpotential <W> relaxes from large to small values during the course of inflation. However, our toy models do not provide a reasonable fit to cosmological data if one sets the SUSY-breaking scale to m_{3/2} < TeV. Our work is a small step towards relieving the apparent tension between high-scale inflation and low-scale supersymmetry breaking in string compactifications.