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Title: Measurement of the forward-backward asymmetry of top-quark and antiquark pairs using the full CDF Run II data set

In this study, we measure the forward--backward asymmetry of the production of top quark and antiquark pairs in proton-antiproton collisions at center-of-mass energy $$\sqrt{s} = 1.96~\mathrm{TeV}$$ using the full data set collected by the Collider Detector at Fermilab (CDF) in Tevatron Run II corresponding to an integrated luminosity of $$9.1~\rm{fb}^{-1}$$. The asymmetry is characterized by the rapidity difference between top quarks and antiquarks ($$\Delta y$$), and measured in the final state with two charged leptons (electrons and muons). The inclusive asymmetry, corrected to the entire phase space at parton level, is measured to be $$A_{\text{FB}}^{t\bar{t}} = 0.12 \pm 0.13$$, consistent with the expectations from the standard-model (SM) and previous CDF results in the final state with a single charged lepton. The combination of the CDF measurements of the inclusive $$A_{\text{FB}}^{t\bar{t}}$$ in both final states yields $$A_{\text{FB}}^{t\bar{t}}=0.160\pm0.045$$, which is consistent with the SM predictions. We also measure the differential asymmetry as a function of $$\Delta y$$. A linear fit to $$A_{\text{FB}}^{t\bar{t}}(|\Delta y|)$$, assuming zero asymmetry at $$\Delta y=0$$, yields a slope of $$\alpha=0.14\pm0.15$$, consistent with the SM prediction and the previous CDF determination in the final state with a single charged lepton. The combined slope of $$A_{\text{FB}}^{t\bar{t}}(|\Delta y|)$$ in the two final states is $$\alpha=0.227\pm0.057$$, which is $$2.0\sigma$$ larger than the SM prediction.
  1. Univ. of Helsinki, Helsinki (Finland); Helsinki Institute of Physics, Helsinki (Finland). et al.
Publication Date:
Report Number(s):
FERMILAB-PUB-16-045-E; arXiv:1602.09015
Journal ID: ISSN 2470-0010; 1424841; TRN: US1601716
Grant/Contract Number:
AC02-07CH11359; AC02-05CH11231
Accepted Manuscript
Journal Name:
Physical Review D
Additional Journal Information:
Journal Volume: 93; Journal Issue: 11; Journal ID: ISSN 2470-0010
American Physical Society (APS)
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States); Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), High Energy Physics (HEP) (SC-25)
Contributing Orgs:
CDF Collaboration
Country of Publication:
United States
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1255475; OSTI ID: 1454473