Implications of generalizedZ−Z′mixing
We discuss experimental implications of extending the gauge structure of the standard model to include an additional $U(1)$ interaction broken at or near the weak scale. We work with the most general, renormalizable Lagrangian for the $\mathrm{SU}(2)\ifmmode\times\else\texttimes\fi{}U(1)\ifmmode\times\else\texttimes\fi{}U(1)$ sector, with emphasis on the phenomenon of gauge kinetic mixing between the two $U(1)$ gauge fields, and do not restrict ourselves to any of the ``canonical'' ${Z}^{\ensuremath{'}}$ models often discussed in the literature. Low-energy processes and ${Z}^{0}$-pole precision measurements are specifically addressed.