A scenario of heavy but visible baryonic dark matter

TL;DR

This paper proposes a model where dark matter is a heavy, composite baryon from a dark sector, with a calculable relic abundance, potential decay signatures, and observable cosmic ray and gamma-ray signals.

Contribution

It introduces a novel dark matter model based on a dark QCD-like sector with accidental stability, predicting a heavy mass and decay signatures consistent with current observations.

Findings

Dark matter mass predicted to be around 100 TeV for correct relic abundance.

Dark matter decay lifetime can explain AMS-02 anti-proton excess.

Potential gamma-ray and neutrino signals from dark matter decay.

Abstract

We consider a model in which dark matter is a composite baryon of a dark sector governed by $SU(3)$ gauge theory, with vector-like quarks also charged under $U(1)_Y$. The model provides simple answer to the dark matter stability problem: it is a result of the accidental dark baryon number conservation. And with an analogy to QCD, all physical quantities of the dark matter can be calculated by rescaling the QCD experimental results. According to the thermal freeze-out mechanism the mass of the dark matter is predicted to be $\mathcal{O}(100)$~TeV in order to achieve a correct relic abundance. Such heavy dark matter is in general hard for detection due to small dark matter number density in the universe. However, dark baryon number in our model is not necessarily strictly preserved thanks to operators suppressed by the Planck scale, and such decay operator results in a decay lifetime marginal to the current detection bound. We show our model with $\mathcal{O}(10^{27})~s$ dark matter decay life time can explain the AMS-02 anti-proton data, if it is experimentally interpreted as an access, although some theoretical uncertainty may weaken its significance. We also investigate other phenomena of this model such as the extragalactic gamma ray and neutrino signatures.