Dark baryon from pure Yang-Mills theory and its GW signature from cosmic strings

TL;DR

This paper proposes a dark matter candidate from pure Yang-Mills theory, specifically a baryonic glueball, which is stable and can produce detectable gravitational wave signals from cosmic strings, potentially explaining recent pulsar timing array observations.

Contribution

It introduces a novel dark matter candidate from SO(2N) Yang-Mills theory and links cosmic string gravitational wave signals to this model, including recent pulsar timing array data.

Findings

Baryonic glueballs are stable dark matter candidates.

Cosmic string dynamics produce gravitational waves detectable by pulsar timing arrays.

The model can explain both dark matter abundance and recent GW signals.

Abstract

We point out that SO($2N$) pure Yang-Mills theory provides a candidate for dark matter (DM) without the explicit need to impose any additional symmetry. The DM candidate is a particular type of glueball, which we refer to as a baryonic glueball, that is naturally stable and produced by a novel production mechanism for a moderately large $N$. In this case, the intercommutation probability of cosmic strings (or macroscopic color flux tubes) is quite low, which offers characteristic gravitational wave signals to test our model. In particular, our model can simultaneously account for both abundance of DM and the recently reported gravitational wave signals detected in pulsar timing array experiments, including NANOGrav.