## Singlino-dominated lightest supersymmetric particle as a CDM candidate in supersymmetric models with an extra U(1)

We consider a singlino-dominated neutralino in supersymmetric models with an extra U(1). In case both the {mu} term and also the Z{sup '} mass are generated by the vacuum expectation value of the scalar component of the same singlet chiral superfield, generically the lightest neutralino is not expected to be dominated by the singlino. However, if the gaugino corresponding to the extra U(1) is sufficiently heavy, the lightest neutralino can be dominated by the singlino and still satisfy the constraints resulting from the Z{sup '} phenomenology. We assume a supersymmetry breaking scenario in which the extra U(1) gaugino can bemore »