Publication
Title
Measurement of the helicity fractions of **W** bosons from top quark decays using fully reconstructed $t\overline{t}$ events with CDF II
Author
Institution/Organisation
CDF Collaboration
Abstract
 We present a measurement of the fractions F0 and F+ of longitudinally polarized and right-handed W bosons in top-quark decays using data collected with the CDF II detector. The data set used in the analysis corresponds to an integrated luminosity of approximately 318  pb-1. We select tt̅ candidate events with one lepton, at least four jets, and missing transverse energy. Our helicity measurement uses the decay angle θ*, which is defined as the angle between the momentum of the charged lepton in the W boson rest frame and the W momentum in the top-quark rest frame. The cos⁡θ* distribution in the data is determined by full kinematic reconstruction of the tt̅ candidates. We find F0=0.85-0.22+0.15(stat)±0.06(syst) and F+=0.05-0.05+0.11(stat)±0.03(syst), which is consistent with the standard model prediction. We set an upper limit on the fraction of right-handed W bosons of F+<0.26 at the 95% confidence level.
Language
English
Source (journal)
Physical review : D : particles and fields. - Lancaster, Pa, 1970 - 2003
Publication
Lancaster, Pa : 2007
ISSN
0556-2821
Volume/pages
75:5(2007), p. 052001,1-052001,11
ISI
000245333000003
Full text (Publishers DOI)
Full text (open access)
UAntwerpen
 Faculty/Department Publication type Subject Affiliation Publications with a UAntwerp address