Effects of extra U(1)'s inSU(3)L⊗U(1)and other models

We have analyzed the implications of extra U(1)'s in ${\mathrm{SU}\mathrm{}\left(3\right)\mathrm{}}_L\otimes \mathrm{U}\mathrm{}\left(1\right)\mathrm{}$ electroweak models. We characterize the models by one parameter, the value of which fixes the charges of the third quark and the third lepton. We discuss the neutral-current effects and compare them with other extra- U(1) models. We introduce two new combinations of left-right asymmetry and polarized forward-backward asymmetries which could be sensitive in distinguishing various models when such measurements become available.