Suppressing gravitino thermal production with a temperature-dependent messenger coupling

TL;DR

This paper proposes a mechanism in gauge-mediated supersymmetry breaking models where a temperature-dependent messenger coupling suppresses gravitino production, easing cosmological constraints and enabling compatibility with thermal leptogenesis.

Contribution

It introduces a novel temperature-dependent messenger coupling via an extra singlet field, significantly reducing gravitino relic abundance constraints in GMSB theories.

Findings

Gravitino production can be suppressed by a temperature-dependent coupling.

The relic gravitino abundance aligns with observed dark matter.

The model allows high reheating temperatures compatible with leptogenesis.

Abstract

We show that the constraints on GMSB theories from the gravitino cosmology can be significantly relaxed if the messenger-spurion coupling is temperature dependent. We demonstrate this novel mechanism in a scenario in which this coupling depends on the VEV of an extra singlet field $S$ that interacts with the thermalized plasma which can result in a significantly suppressed gravitino production rate. In such a scenario the relic gravitino abundance is determined by the thermal dynamics of the $S$ field and it is easy to fit the observed dark matter abundance evading the stringent constraints on the reheating temperature, thus making gravitino dark matter consistent with thermal leptogenesis.