Measurement of the Inclusive Forward-Backward ttProduction Asymmetry and its Rapidity Dependence dAfb/d(y).

[摘要] Early measurements of a large forward-background asymmetry at the CDF and D0 experiments at Fermilab have generated much recent interest, but were hampered by large uncertainties. We present here a new measurement of the corrected forward-backward asymmetry of pair-produced top quarks, using a high-statistics sample with much improved precision.We study the rapidity, ytop, of the top quark production angle with respect to the incoming parton momentum in both the lab and tt rest frames.We find the corrected forward-backward asymmetries to beAfb(pp) = 0.150 ± 0.050stat ± 0.024systAfb(tt) = 0.158 ± 0.072stat ± 0.024systThese results should be compared with the small lab pp frame charge asymmetry expected in QCD at NLO, Afb = 0.050 ± 0.015 [7, 8, 9, 10]. Additionally, we introduce a measurement of the Afb rapidity dependence dAfb/d(delta y).We find this to beAfb(|delta y| < 1.0) = 0.026 ± 0.104stat ± 0.012systAfb(|delta y| > 1.0) = 0.611 ± 0.210stat ± 0.246systwhich we compare with model predictions 0.039 ± 0.006 and 0.123 ± 0.018 for the inner and outer rapidities, respectively.

[发布机构] University of Michigan

[效力级别] Ttbar

[关键词] Afb;Ttbar;Asymmetry;Forward-backward;Physics;Science;Physics