Dark matter searches with a mono-Z ′ jet
Yang Bai (Department of Physics, University of Wisconsin-Madison, 1150 University Avenue, Madison, WI, 53706, USA); James Bourbeau (Department of Physics, University of Wisconsin-Madison, 1150 University Avenue, Madison, WI, 53706, USA); Tongyan Lin (Kavli Institute for Cosmological Physics, University of Chicago, 5620 South Ellis Avenue, Chicago, IL, 60637, USA)
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.
