WIMP Dark Matter Hidden behind its Companion

TL;DR

This paper proposes a novel mechanism where WIMP dark matter with a companion particle can evade direct detection constraints by semi-annihilating into its companion, making it difficult to detect with current methods.

Contribution

The paper introduces a new semi-annihilation mechanism involving a companion particle that allows WIMP dark matter to evade direct detection constraints in ZN symmetric models.

Findings

Dark matter can semi-annihilate into its companion, avoiding direct detection signals.

The mechanism is effective for models with N > 2 in ZN symmetry.

Detection becomes challenging at or above TeV mass scales.

Abstract

The WIMP dark matter (DM) hypothesis now is in an awkward position, owing to the stronger and stronger exclusion from DM direct detection. In this article we design a mechanism to evade this constraint.The idea is simple. DM has a companion, and they are both charged under the DM protecting symmetry G; they admit the trilinear coupling DM-DM-companion, so the latter provides a portal to the standard model (SM) via, for instance, the coupling to Higgs doublet.Then, DM semi-annihilates into the companion to arrive correct relic density, without leaving DM-nucleon scattering signal. The idea can be realized for ZN symmetric models with N >2.We stress that this mechanism has the characteristics of co-annihilation, and as a matter of fact its effect becomes necessary near or above the TeV region. This means that it may be difficult to detect our dark matter directly or indirectly.