Return to search

Measurement of the W Boson Helicity in Top Quark Decays

A measurement of the fraction, f⁺, of right-handed W bosons produced in top quark decays is presented. This analysis is based on a sample corresponding to an integrated luminosity of 370 pb⁻¹, collected by the D⊘ detector at the Fermilab Tevatron pp Collider at √s = 1.96 TeV. The helicity angle, θ*, is reconstructed for each lepton. f⁺ is determined by comparing the cos θ* distribution from the data with that for the expected background and signal for various values of f⁺. The fraction of longitudinal W bosons, f⁰, is assumed to be 0.7 as predicted by the standard model. This yields f⁺ = 0.109 ± 0.094 (stat) ± 0.063 (syst), consistent with the standard model prediction of f⁺ = 3.6× 10⁻⁴. The possibility that both f⁺ and f⁰ stray from standard model values is also investigated. In this case cos θ* distributions for each possible W helicity state, along with the backgrounds, are fit to the cos θ* distribution for the data. The best fit values are f⁺ = 0.82 ± 0.30(stat) and f⁰ = −0.58 ± 0.50(stat).

Identiferoai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/195885
Date January 2007
CreatorsGmyrek, Bryan David
ContributorsJohns, Kenneth A., Varnes, Erich W., Johns, Kenneth A., Varnes, Erich W., Fang, Li-Zhi, Garcia, J.D., Milsom, Drew
PublisherThe University of Arizona.
Source SetsUniversity of Arizona
LanguageEnglish
Detected LanguageEnglish
Typetext, Electronic Dissertation
RightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.

Page generated in 0.0026 seconds