Singlet fermionic dark matter

Abstract

We first review the evidence, production mechanisms, and possible candidates of dark matter. Due to the recent observations on cosmic microwave background anisotropies by WMAP, it is provided that about one fourth of the whole component of our universe is made of non-baryonic dark matter. Explaining this non-baryonic dark matter with right abundance in the present universe is one of the main motivations of theories beyond the Standard Model. We briefly review various candidates of non-baryonic dark matter in such theories. In the meantime, a variety of dark matter detection experiments are being performed and planned. They are classified as the direct detection by the recoil of target nuclei and the indirect detection by observing the other particles which may be produced from dark matter annihilations. We also introduce various direct/indirect detection experiments in this paper. As such a trial to find the right dark matter model, a renormalizable model with a fermionic cold dark matter is proposed, which is a minimal extension beyond the Standard Model motivated only by the existence of dark matter. A minimal hidden sector consisting of a Standard Model gauge singlet Dirac fermion and a real singlet scalar is introduced. We show that the singlet fermion can be a candidate of the cold dark matter which explain the relic abundance measured by WMAP. We call this Singlet Fermionic Dark Matter model. The constraints on the masses and couplings at LEP2 are included and the elastic scattering cross sections for the direct detection are predicted. We find that most region of the parameter set will be probed by the direct detection through elastic scatterings of the dark matter with nuclei in the near future. We also have shown that a simple model of light singlet fermionic dark matter can reconcile the DAMA signal with other null experiments, while providing a right amount of dark matter relic density which is consistent with the WMAP observation. The $\It{t}$-cha...