Direct Measurement of the W Boson Width in ppbar Collisions at roots = 1.8 TeV

This Letter describes a direct measurement of the $W$ boson total decay width, $\gw$, using the Collider Detector at Fermilab. The measurement uses an integrated luminosity of $90\invpb$, collected during the 1994--1995 run of the Fermilab Tevatron $p\pbar$ collider. The width is determined by normalizing predicted signal and background distributions to 49844 $\wenu$ candidates and 21806 $\wmunu$ candidates in the transverse-mass region $M_T<200\gev$ and then fitting the predicted shape to the 438 electron events and 196 muon events in the high-$M_T$ region, $100<M_T<200\gev$. The result is $\Gamma_W=2.04\pm0.11$(stat)$\pm0.09$(syst)GeV.