Published December 1, 2006 | Version v1
Report

Measurement of the helicity fractions of W bosons from top quark decays using fully reconstructed t anti-t events with CDF II

Description

The authors 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. They select t(bar t) candidate events with one lepton, at least four jets, and missing transverse energy. The 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 t(bar t) candidates. They 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. They set an upper limit on the fraction of right-handed W bosons of F+ < 0.26 at the 95% confidence level

Availability note (English)

Available from http://lss.fnal.gov/cgi-bin/find_paper.pl?pub-06-461.pdf; PURL: https://www.osti.gov/servlets/purl/900373-1uXBls/

Additional details

Publishing Information

Imprint Pagination
11 p.
Report number
FERMILAB-PUB--06-461-E

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