Mechanism for dark matter depopulation

TL;DR

This paper proposes a novel cosmological mechanism where dark matter particles become temporarily unstable and decay, effectively reducing their abundance and addressing the issue of overproduction in early universe models.

Contribution

It introduces a new mechanism for dark matter depopulation through temporary instability phases, applicable to various theoretical models including MSSM and scotogenic models.

Findings

Demonstrates the mechanism within a simple fermionic dark matter toy model.

Shows how the mechanism can be integrated into MSSM and scotogenic models.

Provides a potential solution to dark matter overabundance problems.

Abstract

Early decoupling of thermally produced dark matter particles due to feeble interactions with the surrounding plasma typically results in their excessive abundance. In this work we propose a simple mechanism for dark matter depopulation. It relies on a specific cosmological evolution under which dark matter particles become temporarily unstable and hence decay away reducing the overall abundance. The instability phase may be followed by an incomplete regeneration phase until the final abundance is established. We explicitly demonstrate this mechanism within a simple toy model of fermionic dark matter and discuss how it can be implemented in theoretically well motivated theories, such as the minimal supersymmetric standard model (MSSM) and for fermionic dark matter in the scotogenic model.