Searching For Dark Matter Via Mono-Z Boson Production At The ILC

Particle physics is a branch of physics which currently research the structures and properties of the basic matter for the deepest level microscopic world and regulation of the material transformation. Although the Standard Model (SM) achieves great success and the particles which is predicted has been discovered, it appear the problem of quality square divergence for the Higgs boson, namely grade difference problem. The SM has been considered as an effective theory of some new theories in low energy. It is believed that the effect of new physics will emerge in TeV scale. At the same time, we have limited understanding on the universe, such as dark matter (DM).To solve the difficulties in the SM, many extended models are put forward, such as Supersymmetry, Universal extra dimensions, Little Higgs and Two Higgs. High Energy Colliders provide a new unique way to determine the microscopic properties of dark matter. Weakly interacting massive particles (WIMPs) are widely considered as one of the best DM candidates. It is usually assumed that the WIMP couples to the SM sector through its interactions with quarks and leptons. In this thesis, we investigate the DM pair production associated with a Z boson in an effective field theory framework at the international linear collider, which can be used to study the interactions between the DM and leptons. For illustrative purposes, we present the integrated and differential cross sections for thee+e- â†' xxZprocess, where the Z boson is radiated form the initial state electron or positron. Meanwhile, we analyze the neutrino pair production in association with a Z boson as the SM background. In order to search for DM, by adopting appropriate event selection, the backgrounds can also be safely ignored, which will not hurt the signal too much. Provide a theoretical limit for probing DM scale by depict the3σ detection regionmx - Aon the plane. Polarized beams are sensitive to the chirality of the underlying interactions, one of the major advantages of having collider is the possibility of using polarized beams, which often help in reducing the SM backgrounds and significantly enhance the signal rates. Meanwhile, Compared with the leptonic mode, we find that there are more events for the hadronic channel, and the signal significance is also more notable. The current LHC bounds onΛare of the order of 700 GeV, which is lower than at ILC for both mono-photon and mono-Z production. Therefore, we conclude that ILC searches will be more sensitive to much higher scales.