W and Z Physics

The electroweak theory elegantly combines the electromagnetic and weak forces, explaining a wide range of interactions using a gauge theory with just three parameters. The theory predicted the W and Z weak gauge bosons before they were directly observed in 1983, and its detailed predictions of W and Z boson properties have been tested to such precision that they now serve as probes for new particles through loop-level interactions. Currently, the limiting parameter in these probes is the W boson mass, whose uncertainty has been recently reduced by measurements of √ s = 1.96 TeV pp̄ collision data produced by the Fermilab Tevatron. Future measurements at the Tevatron and the Large Hadron Collider will result in nearly a factor of three reduction in the uncertainty on the W boson mass, significantly constraining the Higgs boson mass and the masses and couplings of supersymmetric particles. Other W and Z boson properties recently constrained by measurements at the Tevatron and HERA include their self-couplings and couplings to quarks.