Measurement of leptonic asymmetries and top-quark polarization in t(t)over-bar production
2013 (English)In: Physical Review D, ISSN 1550-7998, Vol. 87, no 1, 011103- p.Article in journal (Refereed) Published
We present measurements of lepton (l) angular distributions in top-quark (t) pair production and t (t) over bar -> W(+)bW-(b) over bar -> l(+) vbl-(v) over bar(b) over bar decays produced in p (p) over bar collisions at a center-of-mass energy of root 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(FB)(l) = (5.8 +/- 5.1(stat) +/- 1.3(syst))%, corrected for detector acceptance. This is compared to the standard model prediction of A(FB)(l)(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(FB)(l) = (11.8 +/- 3.2)%. Furthermore, we present a first study of the top-quark polarization.
Place, publisher, year, edition, pages
2013. Vol. 87, no 1, 011103- p.
IdentifiersURN: urn:nbn:se:uu:diva-195372DOI: 10.1103/PhysRevD.87.011103ISI: 000313946200001OAI: oai:DiVA.org:uu-195372DiVA: diva2:607778