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

Journal Article · Fri Dec 01 04:00:00 EST 2006 · Phys.Rev.D75:052001,2007

OSTI ID:900373

Abulencia, A; Adelman, J; Affolder, T; Akimoto, T; Albrow, M G; Ambrose, D; Amerio, S; Amidei, D; Anastassov, A; Anikeev, K; Annovi, A

The authors 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}. 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 {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 t{bar t} candidates. They 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. They set an upper limit on the fraction of right-handed W bosons of F{sub +} < 0.26 at the 95% confidence level.

• Research Organization: Fermi National Accelerator Laboratory (FNAL), Batavia, IL
• Sponsoring Organization: USDOE
• DOE Contract Number: AC02-07CH11359
• OSTI ID: 900373
• Report Number(s): FERMILAB-PUB-06-461-E; arXiv eprint number hep-ex/0612011
• Journal Information: Phys.Rev.D75:052001,2007, Journal Name: Phys.Rev.D75:052001,2007
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
DECAY
DISTRIBUTION
Experiment-HEP
FERMILAB COLLIDER DETECTOR
FORECASTING
HELICITY
INTERMEDIATE BOSONS
LEPTONS
LUMINOSITY
STANDARD MODEL
T QUARKS
TRANSVERSE ENERGY