Dark Matter searches at ATLAS

Numerous independent astrophysical experiments have observed and measured the influence of the phenomenon named Dark Matter, but its nature is still unknown. If the assumption that Dark Matter is a particle which has a weak coupling to the Standard Model is valid, then collider searches have the ability to search for the production of this new Weakly Interacting Massive Particle (WIMP). Any Dark Matter particles produced in collisions would escape the detector without being observed. Signatures which include an initial-state radiated particle balancing a large amount of Missing Transverse Momentum, known as mono-X topologies, provide a generic means of conducting Dark Matter searches. ATLAS has conducted several mono-X searches, including recoiling jets, photons, W/Z bosons which decay hadronically, and Z bosons which decay leptonically. Searches were carried out with centre of mass energies of both 7 and 8 TeV, and with up to 20/fb of data. No evidence for physics beyond the Standard Model is observed, and thus limits are placed on both Effective Field Theory models and Simplified Models of Dark Matter. These constraints are converted into bounds on WIMP-nucleon cross sections and WIMP annihilation cross-sections.