Dark Sector Searches with CMS and SpinQuest

Many UV complete theories of physics beyond the standard model contain extended gauge sectors or scalar sectors that predict new particles detectable at accelerator experiments. Such particles are also motivated from the bottom-up point of view of thermal dark matter and portal interactions or as candidates to explain muon g-2 and lepton flavor universality violation. In this talk I will motivate and describe recent CMS searches for light dark sector mediators at the LHC. These searches use exotic decays of the Higgs and Z bosons as the source for dark sector particle production and are sensitive to models that explain the experimental anomalies. I will also describe SpinQuest, a fixed-target experiment at Fermilab that provides complementary sensitivity to collider-based dark sector searches. Finally I will describe a proposed upgrade to SpinQuest called DarkQuest that would install an electromagnetic calorimeter and enable an array of new dark sector searches.