Precision electroweak experiments and heavy physics: A global analysis

The radiative corrections of heavy degenerate and nondegenerate electroweak multiplets do not decouple from low-energy experiments. Their effects can be parametrized in a general renormalization-scheme-independent way. For isospin-breaking ${\mathit{h}}_{\mathit{V}}$ and chiral-breaking ${\mathit{h}}_{\mathit{A}\mathit{Z}}$ and ${\mathit{h}}_{\mathit{A}\mathit{W}}$, derived from the Z and W self-energies, a global analysis of existing neutral-current and Z and W data yields -1.2<${\mathit{h}}_{\mathit{V}}$<0.9, -3.5<${\mathit{h}}_{\mathit{A}\mathit{Z}}$<1.0, -4.4<${\mathit{h}}_{\mathit{A}\mathit{W}}$<2.4 (90% C.L.). The expectations for future experiments are described, and the implications for the top-quark and Higgs-boson masses, new generations, supersymmetry, and technicolor are discussed.