M. Acciarri et al., MEASUREMENT OF W-PAIR CROSS-SECTIONS IN E(-)-INTERACTIONS AT ROOT-S=172-GEV AND W-DECAY BRANCHING FRACTIONS()E(), Physics letters. Section B, 407(3-4), 1997, pp. 419-431
We report on the measurement of W-boson pair-production with the L3 de
tector at LEP at an average centre-of-mass energy of 172.13 GeV. In a
data sample corresponding to a total luminosity of 10.25 pb(-1) we sel
ect 110 four-fermion events with pairs of hadronic jets or leptons wit
h high invariant masses. Branching fractions of W decays into differen
t fermion-antifermion pairs are determined with and without the assump
tion of charged-current lepton universality. The branching fraction fo
r hadronic W decays is measured to be: B(W --> hadrons) = 64.2(-3.8)(3.7) (stat.) +/- 0.5 (syst.) %. Combining all final states the total c
ross section for W-pair production is measured to be: sigma(ww) = 12.2
7(-1.32)(+1.41) (stat.) +/- 0.23 (syst.) pb. The results are in good a
greement with the Standard Model. (C) 1997 Elsevier Science B.V.