W boson polarization at LEP2

Elements of the spin density matrix for W bosons in e+e- -> W+W- -> qqln events are measured from data recorded by the OPAL detector at LEP. This information is used calculate polarised differential cross-sections and to search for CP-violating effects. Results are presented for W bosons produced in e+e- collisions with centre-of-mass energies between 183 GeV and 209 GeV. The average fraction of W bosons that are longitudinally polarised is found to be (23.9 +- 2.1 +- 1.1)% compared to a Standard Model prediction of (23.9 +- 0.1)%. All results are consistent with CP conservation.

Note:

20 pages, 3 figures, Submitted to Phys. Letts. B Report-no: CERN-EP/2003-088

electron positron: colliding beams
electron positron: annihilation
W: pair production
W: hadronic decay
W: leptonic decay
W: polarization
polarization: longitudinal
spin: density matrix
differential cross section: angular dependence
polarization: dependence

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Figures(0)

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