Ultraviolet Running Constraints on Low Mass Dark Sectors

We analyze the UV breakdown of Sub-GeV dark matter models that live in a new, dark U(1) sector. Many of these models include a scalar field, which is either the dark matter itself or a dark Higgs field that generates mass terms for the dark matter particle via spontaneous symmetry breaking. A quartic self coupling of this scalar field is generically allowed, and we show that its running is largely governed by the strength of the U(1) gauge field, $\alpha_D$. Furthermore, it consistently has a lower Landau pole than the gauge coupling. Link fields, which couple to both the dark sector and the Standard Model (SM), connect these Landau poles to constraints on SM charged particles. Current LHC constraints on link fields are compatible with $\alpha_D \lesssim 0.5 - 1$ for most of the mass range in most models, while smaller values, $\alpha_D \lesssim 0.15$, are favored for Majorana DM.