A new probe of dark sector dynamics at the LHC

We propose a LHC search for dilepton resonances in association with large missing energy as a generic probe of TeV dark sector models. Such resonances can occur if the dark sector includes a U(1) gauge boson, or Z^′, which kinetically mixes with the Standard Model U(1). For small mixing, direct 2→1 production of the Z^′ is not visible in standard resonance searches due to the large Drell-Yan background. However, there may be significant production of the Z^′ boson in processes involving other dark sector particles, resulting in final states with a Z^′ resonance and missing transverse momentum. Examples of such processes include cascade decays within the dark sector and radiation of the Z^′ off of final state dark sector particles. Even when the rate to produce a Z^′ boson in a dark sector process is suppressed, this channel can provide better sensitivity than traditional collider probes of dark sectors such as monojet searches. We find that data from the 8 TeV LHC run can be interpreted to give bounds on such processes; more optimized searches could extend the sensitivity and continue to probe these models in the Run II data.