Gravitino Problem in Minimal Supergravity Inflation

Understand

We study non-thermal gravitino production in the minimal supergravity inflation.

• In this minimal model utilizing orthogonal nilpotent superfields, the particle spectrum includes only graviton, gravitino, inflaton, and goldstino.
• We find that a substantial fraction of the cosmic energy density can be transferred to the longitudinal gravitino due to non-trivial change of its sound speed.
• This implies either a breakdown of the effective theory during reheating or a serious gravitino problem.