Search for Dark Matter produced in association with a $W$ or $Z$ boson with the ATLAS Experiment at 13 TeV

Dark Matter comprises a significant part of the visible Universe. Despite a solid cosmological evidence, its particle nature and properties is still to be unraveled. Looking for the production of Dark Matter particles at particle colliders can shed light on the mystery of Dark Matter. The signature of this search is a pair of quarks coming from the decays of the Standard Model $W$ and $Z$ bosons, recoiling against missing transverse momentum from Dark Matter particles. Different topologies, such as small$-R$ jets and large$-R$ jets, are considered to identify hadronic decays of highly boosted W and Z bosons. The results using 36 fb$^{−1}$ of 2015+2016 ATLAS pp collision data are presented. Limits on a vector mediator model benchmark model as well as limits with reduced model dependence at 95% confidence level on the visible cross-section of $W/Z$ + Dark Matter production will be presented.