Revival of the thermal sneutrino dark matter

The left-handed sneutrino in the minimal supersymmetric standard model (MSSM) has been ruled out as a viable thermal dark matter candidate, due to conflicting constraints from direct detection experiments and from the measurement of the dark matter relic density. The intrinsic fine-tuning problem of the MSSM, however, motivates an extension with a new $U(1{)}^{\prime }$ gauge symmetry. We show that in the $U(1{)}^{\prime }$-extended MSSM the right-handed sneutrino ${\tilde{\nu }}_R$ becomes a good thermal dark matter candidate. We identify two generic parameter space regions where the combined constraints from relic density determinations, direct detection, and collider searches are all satisfied.