Abstract
We study the dark matter (DM) discovery prospect and its spin discrimination in the theoretical framework of gauge invariant and renormalizable Higgs portal DM models at the ILC with sqrt{s} = 500 GeV. In such models, the DM pair is produced in association with a Z boson. In the case of the singlet scalar DM, the mediator is just the SM Higgs boson, whereas for the fermion or vector DM there is an additional singlet scalar mediator that mixes with the SM Higgs boson, which produces significant observable differences. After careful investigation of the signal and backgrounds both at parton level and at detector level, we find the signal with hadronically decaying Z boson provides a better search sensitivity than the signal with leptonically decaying Z boson. Taking the fermion DM model as a benchmark scenario, when the DM-mediator coupling g_chi is relatively small, the DM signals are discoverable only for benchmark points with relatively light scalar mediator H_2. The spin discriminating from scalar DM is always promising, while it is difficult to discriminate from vector DM. As for g_chi approaching the perturbative limit, benchmark points with the mediator H_2 in the full mass region of interest are discoverable. The spin discriminating aspects from both the scalar and the fermion DM are quite promising.
Highlights
O(100) GeV and interacts with Standard Model (SM) particles via the electroweak force
The corresponding cut on BDT for each benchmark point in the fermion DM (FDM) model that maximizes the signal significance is given in the Table 3, where we provide the numbers of signal and background events and the signal significance after the BDT cut
We have considered the dark matter (DM) discovery prospect and its spin discrimination at the ILC in the theoretical framework of gauge invariant and renormalizable Higgs portal DM
Summary
O(100) GeV and interacts with Standard Model (SM) particles via the electroweak force. The simplest ones are singlet DM extension of SM with Higgs portal In these models, depending on the DM spin, the gauge invariant DM-SM interactions may require at least two mediators. In this work, based on the gauge invariant and renormalizable DM models with Higgs portal, we will study the fermion DM (FDM) discovery prospects and its spin discriminations against scalar DM (SDM) and vector DM (VDM) at the ILC. 2, we briefly describe the renormalizable and gauge invariant Higgs portal DM models for scalar, fermion and vector DM Their complete Lagrangians as well as the interaction Lagrangians that are relevant to the DM search at collider are provided.
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