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Phys. Rev. D 75, 031102(R) (2007) [8 pages]

Measurement of the W boson helicity in top quark decays at D0

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V. M. Abazov et al. D0 Collaboration
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Received 26 September 2006; published 5 February 2007

We present a measurement of the fraction f+ of right-handed W bosons produced in top quark decays, based on a candidate sample of tt̅ events in the +jets and dilepton decay channels corresponding to an integrated luminosity of 370  pb-1 collected by the D0 detector at the Fermilab Tevatron pp̅ Collider at s=1.96  TeV. We reconstruct the decay angle θ* for each lepton. By comparing the cos⁡θ* distribution from the data with that for the expected background and signal for various values of f+ (where we assume that the fraction of longitudinally-polarized W bosons has the standard model value of 0.70), we find f+=0.056±0.080(stat)±0.057(syst) (f+<0.23 at 95% C.L.), consistent with the standard model prediction of f+=3.6×10-4.

© 2007 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevD.75.031102
DOI:
10.1103/PhysRevD.75.031102
PACS:
14.70.Fm, 12.15.Ji, 14.65.Ha