We explore the possibility that dark matter (DM) is the lightest hadron made of two stable color octet Dirac fermions $\mathcal{Q}$. The cosmological DM abundance is reproduced for $M_{\mathcal{Q}}\approx 12.5\mathrm{TeV}$, compatibly with direct searches (the Rayleigh cross section, suppressed by $1/M_{\mathcal{Q}}^6$, is close to present bounds), indirect searches (enhanced by $\mathcal{Q}\mathcal{Q}+\overline{\mathcal{Q}}\overline{\mathcal{Q}}\to \mathcal{Q}\overline{\mathcal{Q}}+\mathcal{Q}\overline{\mathcal{Q}}$ recombination), and with collider searches (where $\mathcal{Q}$ manifests as tracks, pair produced via QCD). Hybrid hadrons, made of $\mathcal{Q}$ and of standard model quarks and gluons, have large QCD cross sections, and do not reach underground detectors. Their cosmological abundance is $10^5$ times smaller than DM, such that their unusual signals seem compatible with bounds. Those in the Earth and stars sank to their centers; the Earth crust and meteorites later accumulate a secondary abundance, although their present abundance depends on nuclear and geological properties that we cannot compute from first principles.

• Received 15 January 2018

DOI:https://doi.org/10.1103/PhysRevD.97.115024

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Published by the American Physical Society