Implications of Dark Matter in Supersymmetric Models

Supersymmetry is a proposed new symmetry that relates bosons and fermions. If supersymmetry is realized in nature, it could provide a solution to the hierarchy problem, and one of the new particles it predicts could explain dark matter. In this thesis, I study supersymmetric models in which the lightest supersymmetric particle can be responsible for dark matter. I discuss a scenario in which the supersymmetric partner of the top quark called stop is the next-to-lightest supersymmetric particle in the constrained Minimal Supersymmetric Standard Model. Mass limits and various decay branching fractions are considered when the allowed parameter space for the scenario is determined. If the mass of stop is close to the mass of the lightest supersymmetric particle, one can obtain the observed dark matter density. The scenario leads to a novel experimental signature consisting of high transverse momentum top jets and large missing energy, which can be used to probe the model at the LHC. I also discuss an extended supersymmetric model with spontaneous chargeparity (CP) violation and a right-handed neutrino. When CP is spontaneously violated, a light singlet scalar appears in the particle spectrum, which provides new annihilation channels for the lightest supersymmetric particle. In the model, a neutralino or a right-handed sneutrino can produce the observed dark matter density. Dark matter direct detection limits are found to be especially constraining for right-handed sneutrinos.