Comparison of neutralino and sneutrino dark matter in a model with spontaneous CP violation

Supersymmetric extensions to the standard model provide viable dark matter candidates and can introduce additional charge-parity (CP) violation needed for obtaining the observed baryon asymmetry of the universe. We study the possibilities of scalar and neutralino dark matter with spontaneous CP violation in the next-to-minimal supersymmetric standard model with a right-handed neutrino. The observed relic density can be produced both by a neutralino or a right-handed sneutrino as the lightest supersymmetric particle but when CP is violated new annihilation channels become available and in general lower the relic density. We consider collider phenomenology for a number of benchmark points which all satisfy experimental constraints and have either the neutralino or the right-handed sneutrino contribute to the dark matter abundance.