Dark matter searches with a mono-Z′ jet

Abstract

Abstract: We study collider signatures of a class of dark matter models with a GeV-scale dark Z′. At hadron colliders, the production of dark matter particles naturally leads to associated production of the Z′, which can appear as a narrow jet after it decays hadronically. Contrary to the usual mono-jet signal from initial state radiation, the final state radiation of dark matter can generate the signature of a mono-Z′ jet plus missing transverse energy. Performing a jet-substructure analysis to tag the Z′ jet, we show that these Z′ jets can be distinguished from QCD jets at high significance. Compared to mono-jets, a dedicated search for mono-Z′ jet events can lead to over an order of magnitude stronger bounds on the interpreted dark matter-nucleon scattering cross sections.