Topological Freeze-out by Semi-Annihilation

TL;DR

This paper proposes a natural dark matter model involving a QCD-like dark sector coupled via topological current gauging, where semi-annihilation processes determine relic abundance and are free from indirect detection constraints.

Contribution

It introduces a novel dark matter scenario with topological interactions that enable semi-annihilation, avoiding indirect detection limits and allowing for diverse experimental probes.

Findings

Dark matter pion mass range is 10 MeV to 1 TeV.

Semi-annihilation is p-wave and avoids indirect detection constraints.

Potential for detection at colliders and low-energy experiments.

Abstract

We point out that a QCD-like dark sector can be coupled to the Standard Model by gauging the topological Skyrme current, which measures the dark baryon number in the infrared, to give a technically natural model for dark matter. This coupling allows for a semi-annihilation process $\chi \chi \rightarrow \chi X_\mu$, where $X_\mu$ is the gauge boson mediator and $\chi$ a dark pion field, which plays the dominant role in setting the dark matter relic abundance. The topological interaction is purely $p$-wave and so free from indirect detection constraints. We show that the dark matter pion mass needs to be in the range $10$ MeV $\lesssim m_\chi \lesssim$ $1$ TeV; towards the lighter end of this range, there can moreover be significant self-interactions. We discuss prospects for probing this scenario at collider experiments, ranging from the LHC to low-energy $e^+ e^-$ colliders, future Higgs factories, and beam-dump experiments.