Direct measurement of the W boson width in p(p)over-bar collisions at root s=1.96 TeV

A direct measurement of the total decay width of the W boson Gamma(W) is presented using 350 pb(-1) of data from p (p) over bar collisions at root s = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. The width is determined by normalizing predicted signal and background distributions to 230 185 W candidates decaying to e nu and mu nu in the transverse-mass region 50 < M(T) < 90 GeV and then fitting the predicted shape to 6055 events in the high-M(T) region, 90 < M(T) < 200 GeV. The result is Gamma(W) = 2032 +/- 45(stat) +/- 57(syst) MeV, consistent with the standard model expectation.