Model-Independent Measurement of the W-Boson Helicity in Top-Quark Decays at D0

Journal Article · Fri Feb 15 04:00:00 EST 2008 · Physical Review Letters

DOI:https://doi.org/10.1103/PHYSREVLETT.100.062004· OSTI ID:21024756

Abazov, V M; Alexeev, G D; Kalinin, A M; Kharzheev, Y M; Malyshev, V L; Tokmenin, V V; Vertogradov, L S; Yatsunenko, Y A ^[1]; Abbott, B; Gutierrez, P; Hossain, S; Jain, S; Rominsky, M; Severini, H; Skubic, P; Strauss, M ^[2]; Abolins, M; Benitez, J A; Brock, R; Dyer, J ^[3]

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1. Joint Institute for Nuclear Research, Dubna (Russian Federation)
2. University of Oklahoma, Norman, Oklahoma 73019 (United States)
3. Michigan State University, East Lansing, Michigan 48824 (United States)

We present the first model-independent measurement of the helicity of W bosons produced in top quark decays, based on a 1 fb{sup -1} sample of candidate tt events in the dilepton and lepton plus jets channels collected by the D0 detector at the Fermilab Tevatron pp Collider. We reconstruct the angle {theta}* between the momenta of the down-type fermion and the top quark in the W boson rest frame for each top quark decay. A fit of the resulting cos{theta}* distribution finds that the fraction of longitudinal W bosons f{sub 0}=0.425{+-}0.166(stat){+-}0.102(syst) and the fraction of right-handed W bosons f{sub +}=0.119{+-}0.090(stat){+-}0.053(syst), which is consistent at the 30% C.L. with the standard model.

• OSTI ID: 21024756
• Journal Information: Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 6 Vol. 100; ISSN 0031-9007; ISSN PRLTAO
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
FERMILAB TEVATRON
HELICITY
LEPTONS
PARTICLE DECAY
STANDARD MODEL
T QUARKS
W MINUS BOSONS
W PLUS BOSONS