A study of sensitivity to extra Z boson at high energy e+e- collider

Effects of a new neutral gage boson Z' on cross section, forward-backward asymmetry and polarization asymmetry of e+e- reactions at TeV energy region has been studied. It is shown that dramatic effects can be expected if the mass (MZ') is less than the c.m. energy (Ecm). Also shown is that even if MZ' is well above Ecm, the searchable energy region can be pushed up by the asymmetry measurements to a few times Ecm. In particular, polarized beam is shown to be a powerful and indispensable tool for new physics. (author)