Search

Discovering dark matter at high-energy colliders continues to be a compelling and well-motivated possibility. Weakly interacting massive particles are a particularly interesting class in which the dark matter particles interact with the standard model weak gauge bosons. Neutralinos are a prototypical example that arise in supersymmetric models. In the limit where all other superpartners are decoupled, it is known that for relic density motivated masses, the rates for neutralinos are too small to be discovered at the Large Hadron Collider (LHC), but that they may be large enough to observe at 100 TeV. In this work we perform a careful study in the vector boson fusion channel for pure winos and pure Higgsinos. We find that given a systematic uncertainty of 1% (5%), with 3000 fb-1, the LHC is sensitive to winos of 240 GeV (125 GeV) and Higgsinos of 125 GeV (55 GeV). A future 100 TeV collider would be sensitive to winos of 1.1 TeV (750 GeV) and Higgsinos of 530 GeV (180 GeV) with a 1% (5%) uncertainty, also with 3000 fb-1. [ABSTRACT FROM AUTHOR]

Effective contact operators provide the simplest parametrization of dark matter searches at colliders. However, light mediators can significantly change the sensitivity and search strategies. Considering simple models of mediators is an important next step for collider searches. In this paper, we consider the case of a t-channel mediator. Its presence opens up new contributions to the monojet + ET searches and can change the reach significantly. We also study the complementarity between searches for processes of monojet + ET and direct pair production of the mediators. Mediator pair production also gives an important contribution to a CMS-like monojet + ET search, where a second hard jet is allowed. There is a large region of parameter space in which the monojet + ET search provides the stronger limit. Assuming the relic abundance of the dark matter is thermally produced within the framework of this model, we find that in the Dirac fermion dark matter case, there is no region in the parameter space that satisfies the combined constraint of monojet + ET search and direct detection; whereas in the Majorana fermion dark matter case, the mass of dark matter must be larger than about 100 GeV. If the relic abundance requirement is not assumed, the discovery of the t-channel mediator predicts additional new physics. [ABSTRACT FROM AUTHOR]