Radiative symmetry breaking in a supersymmetric model with an extra U(1)

Radiative symmetry breaking is studied in a superstring-inspired supersymmetric model which is extended with a low energy extra U(1) symmetry. In this model the mu problem is radiatively solved in an automatic way. The right-handed neutrino can be heavy and the seesaw mechanism will produce the small neutrino mass which makes the MSW solution applicable to the solar neutrino problem. We search a parameter region which has the favorable feature for the radiative symmetry breaking at the weak scale. A rather wide parameter region is found to be allowed. Although there are certain dependences on the soft supersymmetry breaking parameters in the estimation of masses of various fields, the upper bound of the extra Z boson mass is estimated to be m(Z2) less than or equal to 2000 GeV for a top mass range 150 GeV less than or equal to mt less than or equal to 190 GeV within a suitable parameter region (m(0) < 1 TeV ana m(1/2) < 200 GeV). Some phenomenological features of the extra Z boson are also and presented.