Neutralinos in E_{6} inspired supersymmetric U(1)' models

The neutralino sector in $\mathrm{E_6}$ inspired supersymmetric models with extra neutral gauge bosons and singlet Higgs fields contains additional gaugino and singlino states compared to the MSSM. We discuss the neutralino mixing in rank-5 and rank-6 models and analyze the supersymmetric parameter space where the light neutralinos have mainly singlino or MSSM character. The neutralino character, resonance effects of the new gauge bosons and, assuming mSUGRA-type RGEs, different selectron masses lead to significant differences between the MSSM and the extended models in neutralino production at an $e^+e^-$ linear collider. Beam polarization may improve the signatures to distinguish between the models. In an appendix, we present the mass terms of the gauge bosons, charginos and sfermions which show a significant different mass spectrum than in the MSSM and give all relevant neutralino couplings.