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

Journal Article · Thu Mar 01 04:00:00 EST 2007 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.75.052001· OSTI ID:21020037

Abulencia, A; Budd, S; Ciobanu, C I; Errede, D; Errede, S; Gerberich, H; Grundler, U; Junk, T R; Kraus, J; Liss, T M; Marino, C P; Pitts, K; Rogers, E; Taffard, A; Veramendi, G; Zhang, X ^[1]; Adelman, J; Brubaker, E; Fedorko, W T; Furic, I ^[2]

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1. University of Illinois, Urbana, Illinois 61801 (United States)
2. Enrico Fermi Institute, University of Chicago, Chicago, Illinois 60637 (United States)

We present a measurement of the fractions F{sub 0} and F{sub +} 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{sup -1}. We select tt candidate events with one lepton, at least four jets, and missing transverse energy. Our helicity measurement uses the decay angle {theta}*, 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{theta}* distribution in the data is determined by full kinematic reconstruction of the tt candidates. We find F{sub 0}=0.85{sub -0.22}{sup +0.15}(stat){+-}0.06(syst) and F{sub +}=0.05{sub -0.05}{sup +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{sub +}<0.26 at the 95% confidence level.

• OSTI ID: 21020037
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 5 Vol. 75; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
DISTRIBUTION
FERMILAB COLLIDER DETECTOR
HELICITY
JET MODEL
LEPTONS
MULTIPARTICLE SPECTROMETERS
PARTICLE DECAY
PARTICLE IDENTIFICATION
PARTICLE KINEMATICS
STANDARD MODEL
T QUARKS
TRANSVERSE ENERGY
W MINUS BOSONS
W PLUS BOSONS