Freeze-in and Freeze-out in a Right-Handed Neutrino Extended MSSM with a Seesaw Mechanism

TL;DR

This paper explores dark matter production in a supersymmetric model extended with right-handed neutrinos, analyzing the interplay of freeze-in and freeze-out mechanisms and their implications for relic density constraints.

Contribution

It introduces a scenario with dual dark matter sources via freeze-in and freeze-out in a low-scale seesaw extended MSSM, and rules out certain models based on sterile neutrino decay constraints.

Findings

Sterile neutrinos produced via Dodelson-Widrow mechanism decay too quickly, exceeding the universe's age.

The proposed dual-source dark matter scenario is incompatible with observed relic density constraints.

Right-handed sneutrinos cannot account for dark matter in the considered models due to decay constraints.

Abstract

We investigate the possibility of saturating the relic density bound with light Higgsinos. When the minimal supersymmetric Standard Model is extended with right-handed neutrino superfields and the seesaw scale is very low, right-handed sneutrinos can be produced via the freeze-in mechanism. In such a case we can have essentially two independent sources for dark matter, the traditional freeze-out of Higgsinos and the freeze-in of right-handed sneutrinos. The heavier of these two will decay to the lighter species with a delay. We rule out such a scenario for all seesaw models as the lifetime of sterile neutrinos produced over-abundantly via Dodelson-Widrow mechanism exceeds the age of the universe and will contribute to the relic density.