The gravitino abundance in supersymmetric `new' inflation models

TL;DR

This paper analyzes the production of gravitinos from vacuum fluctuations in new inflation models, showing that their abundance can surpass thermal production and impose stricter cosmological constraints.

Contribution

It provides a detailed calculation of gravitino abundance from vacuum fluctuations in supersymmetric new inflation models, highlighting its significance over thermal production.

Findings

Vacuum fluctuation production can dominate gravitino abundance.

Gravitino abundance may exceed thermal production in certain parameter regimes.

Results lead to tighter cosmological constraints on inflation models.

Abstract

We consider the abundance of gravitinos created from the vacuum fluctuation, in a class of `new' inflation models for which global supersymmetry is a good approximation. Immediately after inflation, gravitinos are produced, with number density determined by equations recently presented by Kallosh et. al. (hep-th/9907124) and Giudice et. al. (hep-ph/9907510). Unless reheating intervenes, creation may continue, maintaining about the same number density, until the Hubble parameter falls below the gravitino mass. In any case, the abundance of gravitinos created from the vacuum fluctuation exceeds the abundance from thermal collisions in a significant regime of parameter space, leading to tighter cosmological constraints.