Leptophilic dark matter with Z' interactions

We consider a scenario where dark matter (DM) interacts exclusively with Standard Model leptons at tree level. Because of the absence of tree-level couplings to quarks, the constraints on leptophilic dark matter arising from direct detection and hadron collider experiments are weaker than those for a generic weakly interacting massive particle. We study a simple model in which interactions of DM with Standard Model leptons are mediated by a leptophilic Z^' boson, and determine constraints on this scenario arising from relic density, direct detection, and other experiments. We then determine current LHC limits and project the future discovery reach. We show that, despite the absence of direct interactions with quarks, this scenario can be strongly constrained.