Exclusion bounds for neutral gauge bosons

We study how the recent experimental results constrain the gauge sectors of U ( 1 ) extensions of the standard model using a novel representation of the parameter space. We determine the bounds on the mixing angle between the massive gauge bosons or, equivalently, the new gauge coupling as a function of the mass M Z ' of the new neutral gauge boson Z ' in the approximate range ( 10 - 2 ; 104) 4 ) GeV/c2. /c 2 . We consider the most stringent bounds obtained from direct searches for the Z ' . We also exhibit the allowed parameter space by comparing the predicted and measured values of the rho parameter and those of the mass of the W boson. Finally, we discuss the prospects of Z ' searches at future colliders.