W Boson Mass and Width at the Tevatron

The CDF and DØ experiments at the Tevatron measure the W boson mass and width with high precision. The Run 1 measurements have been combined to yield M_W^Tevatron = 80.456 ± 0.059 GeV and Γ _W^Tevatron = 2.115 ± 0.105 GeV. CDF has analyzed 0.2 fb^-l of Run 2 data and determined the uncertainties on the W boson mass measurements in the electron and muon decay channels. Combining the two channels yields a 76 MeV uncertainty, which is lower than the uncertainty on the Run 1 CDF W boson mass measurement.