# The Case for an EeV Gravitino

## TL;DR

This paper explores the hypothesis that an EeV-scale gravitino, resulting from high-scale supersymmetry breaking, could serve as the Universe's dark matter, with specific cosmological and particle physics implications.

## Contribution

It proposes a model where the gravitino is the sole low-energy remnant of supersymmetry, linking its mass to high-scale SUSY breaking and cosmological constraints.

## Key findings

- Gravitino mass estimated to be around 0.2 EeV.
- Reheating temperature constrained between 10^{10} and 10^{12} GeV.
- Supersymmetric spectrum must be above 10^{13} GeV.

## Abstract

We consider the possibility that supersymmetry is broken above the inflationary mass scale and that the only "low" energy remnant of supersymmetry is the gravitino with mass of order the EeV scale. The gravitino in this class of models becomes a candidate for the dark matter of the Universe. To avoid the over-production of gravitinos from the decays of the next-to-lightest supersymmetric particle we argue that the supersymmetric spectrum must lie above the inflationary mass scale ($M_{\rm SUSY} > 10^{-5} M_{\rm P} \sim 10^{13}$ GeV). Since $m_{3/2} \simeq M_{\rm SUSY}^2/M_{\rm P}$, we expect $m_{3/2} \gtrsim 0.2$ EeV. Cosmological constraints then predict a relatively large reheating temperature between $10^{10}$ and $10^{12}$ GeV.