The Decay of the Inflaton in No-scale Supergravity

TL;DR

This work analyzes inflaton decay in no-scale supergravity and demonstrates that gravitational decay and gravitino production are highly suppressed by the no-scale Kähler structure. The dominant reheating mechanism arises from a non-trivial gauge kinetic function, connecting the reheating temperature to the gaugino–gravitino mass relationship and allowing temperatures compatible with Big Bang Nucleosynthesis and baryogenesis while avoiding gravitino overproduction. The study highlights both the potential of gauge-kinetic channels for reheating and the remaining moduli-borne challenges in no-scale constructions. Overall, no-scale no-scale models offer a pathway to successful reheating with controlled gravitino production, contingent on stabilizing moduli and carefully choosing the gauge kinetic function.

Abstract

We study the decay of the inflaton in no-scale supergravity and show that decay due to the gravitational interactions through supergravity effects is highly suppressed relative to the case in minimal supergravity or models with a generic Kahler potential. We also show that decay to gravitinos is suppressed. We demonstrate that decay and sufficient reheating are possible with the introduction of a non-trivial gauge kinetic term. This channel may be dominant in no-scale supergravity, yet yields a re-heating temperature which is low enough to avoid the gravitino problem while high enough for Big Bang Nucleosynthesis and baryogenesis.