Constraint on the gravitino mass in hybrid inflation

TL;DR

This paper examines the effects of a constant superpotential term on hybrid inflation in supergravity, highlighting issues like gravitino overproduction and cosmic strings, and discusses conditions under which these problems can be mitigated.

Contribution

It analyzes the impact of the constant superpotential term on hybrid inflation dynamics and identifies conditions to avoid related cosmological problems.

Findings

Hybrid inflation faces tuning, gravitino overproduction, and cosmic string formation issues.

Problems are mitigated in gauge-mediated SUSY breaking models with light gravitinos.

Implications for non-thermal leptogenesis are discussed.

Abstract

We revisit the F-term hybrid inflation model in supergravity. In particular, we point out that a constant term in the superpotential has significant effects on the inflaton dynamics. It is shown that the hybrid inflation model suffers from several potential problems: tuning of the initial condition, gravitino overproduction and formation of cosmic strings, for both minimal and non-minimal Kahler potentials. These problems can only be avoided in gauge-mediated SUSY breaking models where the gravitino is relatively light and the constant term in the superpotential is not important. Implications on the non-thermal leptogenesis scenario are also described.