Sneutrino NLSP in the νCMSSM

We extend the constrained minimal supersymmetric model (CMSSM) by adding a right-handed neutrino superfield (nu CMSSM) which decouples close to the GUT scale. We study the effects of a right-handed neutrino on the low energy spectrum and focus on the predictions for dark matter properties. We pay particular attention to the realization of the light (left-handed) sneutrino which can be the next-to-lightest supersymmetric particle (NLSP) with either the neutralino or gravitino as the lightest supersymmetric particle (LSP). Notably, for the case of a neutralino LSP with a sneutrino NLSP, there are new "sneutrino coannihilation regions" which yield the desired thermal neutralino relic density determined by WMAP.