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Forward-Backward Asymmetries of Fourth Family Fermions Through the Z' Models at Linear Colliders

We investigate the forward-backward asymmetries in the pair production of fourth family fermions through the new Z' interactions in the e+e- collisions. The Z' boson having family universal couplings can contribute to the pair production of fourth family fermions via the s-channel exchange. The linear colliders will provide a clean environment for the physics of Z' boson to measure its couplings precisely. The effects of the Z' boson to the asymmetries are shown to be important in some parameter regions for different Z' models. Among these parameters, the invariant mass distribution m_FFbar will be an important measurement to constrain the Z' models. Providing the fourth family fermion exist in an accesssible mass range, a chi^2 analysis can also be used to probe the Z' models at linear collider energies.