W pair production cross-section and W branching fractions in e+ e- interactions at 189-GeV

The cross-section for the process e + e − → W + W − has been measured with the data sample collected by DELPHI at an average centre-of-mass energy of 189 GeV and corresponding to an integrated luminosity of 155 pb −1 . Based on the 2392 events selected as WW candidates, the cross-section for the doubly resonant process e + e − → W + W − has been measured to be 15.83±0.38 (stat) ±0.20 (syst) pb . The branching fractions of the W decay were also measured and found to be in good agreement with the Standard Model expectation. From these a value of the CKM mixing matrix element |V cs |=1.001±0.040 (stat) ±0.020 (syst) was derived.

Note:

16 pages, 4 figures Report-no: CERN-EP-2000-035 Journal-ref: Phys. Lett. B 479 (2000) 89-100

electron positron: colliding beams
electron positron: annihilation
W: pair production
W: leptonic decay
W: hadronic decay
W: branching ratio
CKM matrix matrix
channel cross section
electroweak interaction: validity test
DELPHI

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