Measurement of Top Quark Polarization in Top-Antitop Events from Proton-Proton Collisions at $\sqrt{s}$ = 7  TeV Using the ATLAS Detector

This Letter presents measurements of the polarization of the top quark in top-antitop quark pair events, using 4.7 fb-1 of proton-proton collision data recorded with the ATLAS detector at the Large Hadron Collider at s=7 TeV. Final states containing one or two isolated leptons (electrons or muons) and jets are considered. Two measurements of αℓP, the product of the leptonic spin-analyzing power and the top quark polarization, are performed assuming that the polarization is introduced by either a CP conserving or a maximally CP violating production process. The measurements obtained, αℓPCPC=-0.035±0.014(stat)±0.037(syst) and αℓPCPV=0.020±0.016(stat)-0.017+0.013(syst), are in good agreement with the standard model prediction of negligible top quark polarization.

Note:

6 pages plus author list (19 pages total), 2 figures, 3 tables, submitted to PRL, All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/TOPQ-2012-22/

14.65.Ha
12.38.Qk
top: polarization
p p: scattering
conservation law: CP
CP: violation
top: pair production
ATLAS
CERN LHC Coll
dilepton: final state

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