Direct Observation of Longitudinally Polarised W Bosons
High Energy Physics - Experiment
2012-08-27 v1
Abstract
The three different helicity states of W bosons, produced in the reaction e+e- -> W+W- -> l nu q q~ are studied using leptonic and hadronic W decays at sqrt{s}=183GeV and 189GeV. The W polarisation is also measured as a function of the scattering angle between the W- and the direction of the e- beam. The analysis demonstrates that W bosons are produced with all three helicities, the longitudinal and the two transverse states. Combining the results from the two center-of-mass energies and with leptonic and hadronic W decays, the fraction of longitudinally polarised W bosons is measured to be 0.261 +/- 0.051(stat.) +/- 0.016(syst.) in agreement with the expectation from the Standard Model.
Cite
@article{arxiv.hep-ex/0001016,
title = {Direct Observation of Longitudinally Polarised W Bosons},
author = {L3 Collaboration},
journal= {arXiv preprint arXiv:hep-ex/0001016},
year = {2012}
}