Measurement of the Mass and the Width of the W Boson at LEP
  The mass and the total decay width of the W boson are measured with the L3 detector at the LEP e+e- collider using W-boson pairs produced in 0.7/fb of data collected at centre-of-mass energies between 161 and 209GeV. Combining semi-leptonic and fully-hadronic final states, the mass and the width of the W boson are determined to be mW = 80.270 +/- 0.046 +/- 0.031 GeV and GW = 2.18 +/- 0.11 +/- 0.09 GeV, where the first uncertainty is statistical and the second systematic. 
L3 Collaboration