WIMP Dark Matter at the International Linear Collider

In this study, the sensitivity of future lepton colliders to weakly interacting massive particles (WIMP) dark matter is evaluated assuming WIMP pair production accompanied by a photon from initial state radiation, through which the process can be identified. A full detector simulation for the International Large Detector (ILD) concept at the International Linear Collider (ILC) is performed for a center-of-mass energy of 500 GeV. Energy scales of up to 3 TeV can be tested for different effective operators for WIMP masses almost up to half the center-of-mass energy. The sensitivity benefits from the polarized beams, which can reduce the main SM background from neutrino pair production substantially. In addition, systematic uncertainties are shown to be significantly reduced by combining data with several different polarization configurations. In comparison to a previous study, the reconstruction of the forward detectors has been improved, and the systematic uncertainties are fully treated. The results are also extrapolated to other center-of-mass energies, luminosities, and beam polarizations. This allows us to provide results for the full ILC program, i.e., from 250 GeV to 1 TeV, as well as to give approximate results for other planned lepton colliders.