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 (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 η' meson, and a heavy bound state of N quarks, the dark analog of the Δ⁺⁺ baryon. We show that the latter may freeze-in with an abundance independent of the confinement scale, forming DM-like relics for N ≲ 10, while the former may generate DM via cannibalization and freeze-out. We study the interplay of this two-component DM system, and determine the characteristic ranges of the confinement scale, dark-visible sector temperature ratio, and N that admit non-excluded DM, once effects of self-interaction constraints and bounds on effective degrees of freedom at the BBN and CMB epochs are included.

暗 QCD 扇区是标准模型 (SM) 的一个相对最小的扩展，它承认暗物质 (DM) 候选者，但除了引力相互作用之外不需要通往可见扇区的门户：DM 检测的“噩梦场景”。我们考虑一个隐蔽的暗扇区，其中包含单一风味的光，矢量状暗夸克，在 (N) 下测量。在大 N 极限下，这种单一风味理论变得具有高度预测性，产生了两个 DM 候选者，其质量和动力学由几个参数描述：轻夸克-反夸克束缚态、η'介子的暗模拟和重N夸克的束缚态，Δ ^{++的暗模拟}重子。我们表明，后者可能以与限制规模无关的丰度冻结，形成 N ≲ 10 的 DM 样遗物，而前者可能通过蚕食和冻结产生 DM。我们研究了这种双分量 DM 系统的相互作用，并确定了约束尺度、暗可见扇区温度比和 N 的特征范围，该范围允许非排除 DM，一旦自相互作用约束和界限对有效度的影响包括 BBN 和 CMB 时期的自由度。