Extraction of the width of the W boson from measurements of σ(pp̅→W+X)×B(W^→ev) and σ(pp̅→Z+X)×B(Z^→ee) and their ratio

Abstract

We report on measurements on inclusive cross sections times branching fractions into electrons for W and Z bosons produced in pp̅ collisions at √s=1.8TeV. From an integrated luminosity of 84.5 pb^-1 recorded in 1994-1995 using the DØ detector at the Fermilab Tevatron, we determine σ(pp̅→W+X)×B(W^→eν)=2310±10(stat)±50(syst)±100(lum)pb and σ(pp̅→Z+X)×B(Z^→ee)=221±3(stat)±4(syst)±10(lum)pb. From these, we derive σ(pp̅→W+X)×B(W^→eν)/σ(pp̅→Z+X)×B(Z^→ee)=10.43±0.15(stat)±0.20(syst)±0.10(NLO), B(W^→eν)=0.1044±0.0015(stat)±0.0020(syst)±0.0017(theory)±0.0010(NLO), and Γ_W=2.169±0.031(stat)±0.042(syst)±0.041(theory)±0.022(NLO)GeV. We use the latter to set a 95% confidence level upper limit on the partial decay width of the W boson into nonstandard model final states, Γ_W^inv, of 0.213 GeV. Combining these results with those from the 1992-1993 data gives σ(pp̅→W+X)×B(W^→eν)/σ(pp̅→Z+X)×B(Z^→ee)=10.51±0.25, Γ_W=2.152±0.066GeV, and a 95% C.L. upper limit on Γ_W^inv of 0.191 GeV. Using a sample with a luminosity of 505 nb^-1 taken at √s=630GeV, we measure σ(pp̅→W+X)×B(W^→eν)=658±67pb.