Large $N$-ightmare Dark Matter

Understand

A dark QCD sector is a relatively minimal extension of the Standard Model (SM) that admits Dark Matter (DM) candidates but requires no portal to the visible sector beyond gravitational interactions: A "nightmare scenario" for DM detection.

• We consider a secluded dark sector containing a single flavor of light, vector-like dark quark gauged under $SU(N)$.
• In the large-$N$ limit, this single-flavor theory becomes highly predictive, generating two DM candidates whose masses and dynamics are described by few parameters: A light quark-antiquark bound state, the dark analog of the $\eta'$ meson, and a heavy bound state of $N$ quarks, the dark analog of the $\Delta^{++}$ baryon.
• We show that the latter may freeze-in with an abundance independent of the confinement scale, forming DM-like relics for $N \lesssim 10$, while the former may generate DM via cannibalization and freeze-out.