WW Production Cross Section and W Branching Fractions in e+e- Collisions at 189 GeV

TL;DR

This paper reports precise measurements of W-pair production cross section and W decay branching fractions at 189 GeV, confirming consistency with Standard Model predictions using data from the OPAL detector at LEP.

Contribution

First measurement of W-pair production cross section and W decay branching fractions at 189 GeV with OPAL, improving precision and confirming Standard Model consistency.

Findings

W-pair production cross section measured as 16.30 pb

W boson hadronic branching fraction is 68.32%

Results align with Standard Model expectations

Abstract

From a data sample of 183 pb^-1 recorded at a center-of-mass energy of roots = 189 GeV with the OPAL detector at LEP, 3068 W-pair candidate events are selected. Assuming Standard Model W boson decay branching fractions, the W-pair production cross section is measured to be sigmaWW = 16.30 +- 0.34(stat.) +- 0.18(syst.) pb. When combined with previous OPAL measurements, the W boson branching fraction to hadrons is determined to be 68.32 +- 0.61(stat.) +- 0.28(syst.) % assuming lepton universality. These results are consistent with Standard Model expectations.