Measurement of Leptonic Asymmetries and Top Quark Polarization in ttbar Production

Collaboration, D0 and Bertram, Iain and Borissov, Guennadi and Fox, Harald and Ross, Anthony and Williams, Mark and Ratoff, Peter (2013) Measurement of Leptonic Asymmetries and Top Quark Polarization in ttbar Production. Physical Review D, 87 (1). ISSN 1550-7998

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Abstract

We present measurements of lepton (l) angular distributions in ttbar -> W+ b W- b -> l+ nu b l- nubar bbar decays produced in ppbar collisions at a center-of-mass energy of sqrt(s)=1.96TeV, where l is an electron or muon. Using data corresponding to an integrated luminosity of 5.4fb^-1, collected with the D0 detector at the Fermilab Collider, we find that the angular distributions of l- relative to anti-protons and l+ relative to protons are in agreement with each other. Combining the two distributions and correcting for detector acceptance we obtain the forward-backward asymmetry A^l_FB = (5.8 +- 5.1(stat) +- 1.3(syst))%, compared to the standard model prediction of A^l_FB (predicted) = (4.7 +- 0.1)%. This result is further combined with the measurement based on the analysis of the l+jets final state to obtain A^l_FB = (11.8 +- 3.2)%. Furthermore, we present a first study of the top-quark polarization.

Item Type:
Journal Article
Journal or Publication Title:
Physical Review D
Additional Information:
© 2013 American Physical Society
ID Code:
63395
Deposited By:
Deposited On:
15 Apr 2013 12:45
Refereed?:
Yes
Published?:
Published
Last Modified:
28 Mar 2020 03:13