Off-Diagonal Dark-Matter Phenomenology: Exploring Enhanced Complementarity Relations in Non-Minimal Dark Sectors

TL;DR

This paper investigates multi-component dark sectors where off-diagonal processes dominate, revealing an enhanced complementarity that improves the ability to probe the nature of dark matter.

Contribution

It introduces a scenario where off-diagonal dark-matter processes dominate, highlighting a new, enhanced framework for dark-matter complementarity in non-minimal sectors.

Findings

Off-diagonal processes can dominate over diagonal ones in certain multi-component dark sectors.

Enhanced complementarity relations improve dark matter detection prospects.

The scenario reveals new experimental signatures for multi-component dark matter.

Abstract

In most multi-component dark-matter scenarios, two classes of processes generically contribute to event rates at experiments capable of probing the nature of the dark sector. The first class consists of "diagonal" processes involving only a single species of dark-matter particle -- processes analogous to those which arise in single-component dark-matter scenarios. By contrast, the second class consists of "off-diagonal" processes involving dark-matter particles of different species. Such processes include inelastic scattering at direct-detection experiments, asymmetric production at colliders, dark-matter co-annihilation, and certain kinds of dark-matter decay. In typical multi-component scenarios, the contributions from diagonal processes dominate over those from off-diagonal processes. Unfortunately, this tends to mask those features which are most sensitive to the multi-component nature of the dark sector. In this paper, by contrast, we point out that there exist natural, multi-component dark-sector scenarios in which the off-diagonal contributions actually dominate over the diagonal. This then gives rise to a new, enhanced picture of dark-matter complementarity. In this paper, we introduce a scenario in which this situation arises and examine the enhanced picture of dark-matter complementarity which emerges.