Prospects for a Mono-Z search for new invisible particles with CMS at the HL-LHC

Over the last decade, the experiments at the CERN Large Hadron Collider (LHC) have established a wide range of searches for collider production of dark matter (DM) particles. In run 2 of the LHC, these searches have profited from the unprecedented center-of-mass energy of 13 TeV, which allowed to directly probe previously inaccessible mass ranges. Even so, no evidence has yet been found for the production of DM particles at the LHC. As we approach the era of the upgraded high-luminosity LHC (HL-LHC), which is scheduled to provide a dataset corresponding to 3 ab${}^{-1}$ of proton-proton collisions over the next two decades, it is imperative to understand how the DM search program will profit from this gigantic dataset. In this talk, I will present a study of the HL-LHC sensitivity of a search for new invisible particles, such as DM candidates, in events with a Z boson and missing transverse momentum ("mono-Z'') with the Compact Muon Solenoid detector (CMS). I will discuss the expected experimental conditions and the challenges they pose, present the projected sensitivity estimates, and comment on the complementarity of the mono-Z and other topologies.