ATLAS Sensitivity to WIMP Dark Matter in the Monojet Topology at $\sqrt{s}=14\,\mathrm{TeV}$

Searches for monojet plus missing transverse momentum signatures are sensitive to new phenomena involving invisible particles, such as the pair-production of dark matter, one particularly well motivated possibility. We report on the expected sensitivity to dark matter in monojet signatures at an upgraded LHC with the ATLAS detector. The effective field theory models typically used for monojet dark matter interpretations have validity limitations. These are addressed both through applying additional constraints, and through a first look at the use of simplified models of dark matter pair-production.