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Measurement of leptonic asymmetries and top-quark polarization in tt-bar production
Baringer, Philip S. Bean, Alice Chen, G. Clutter, Justace Randall Sekaric, Jadranka Wilson, Graham Wallace Abazov, V. M. Abbott, B. Acharya, B. S. Adams, M.
Baringer, Philip S.
Bean, Alice
Chen, G.
Clutter, Justace Randall
Sekaric, Jadranka
Wilson, Graham Wallace
Abazov, V. M.
Abbott, B.
Acharya, B. S.
Adams, M.
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Abstract
We present measurements of lepton (ℓ) angular distributions in top-quark (t) pair production and tt-bar→W+bW−b-bar→ℓ+νbℓ−ν-b-ar b-bar decays produced in pp-bar collisions at a center-of-mass energy of s√=1.96 TeV, where ℓ is an electron or muon. Using data corresponding to an integrated luminosity of 5.4 fb(−1), collected with the D0 detector at the Fermilab Tevatron Collider, we measure for the first time the leptonic forward-backward asymmetry in dilepton final states and obtain A(ℓ)(FB)=(5.8±5.1(stat)±1.3(syst))%, corrected for detector acceptance. This is compared to the standard model prediction of A(ℓ)(FB)(predicted)=(4.7±0.1)%. A deviation from the standard model prediction as previously seen in a D0 measurement based on the analysis of the ℓ+jets final state is not observed in these dilepton final states. The two results differ from each other by 1.4 standard deviations and are combined to obtain A(ℓ)(FB)=(11.8±3.2)%. Furthermore, we present a first study of the top-quark polarization.
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This is the publisher's version, also available electronically from http://journals.aps.org/prd/abstract/10.1103/PhysRevD.87.011103.
Date
2013-01-24
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American Physical Society
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V. M. Abazov et al. (D0 Collaboration). (2013). "Measurement of leptonic asymmetries and top-quark polarization in tt-bar production." Physical Review D, 87(1):011103(R). http://www.dx.doi.org/10.1103/PhysRevD.87.011103.