Electroweak Precision Data and a Heavy Z'

Abstract

We consider the physics of an extra $U(1)$ gauge boson $Z^{\prime }$, which can mix with $Z$ through intermediate fermion loops. The loop contribution due to the heavy top quark significantly affects the low-energy observables, and for $m_{Z^{\prime }}>m_Z$, one can always adjust the shifts in these observables to be in the right direction suggested by experiments, when we impose the anomaly cancellation conditions for $Z^{\prime }$.

Comments: LaTeX file, includes postscript of two figures. Title changed in published version. Replaces previous version.