Top charge asymmetry measurement in dileptons at 7 TeV

Abstract

The measurement of the charge asymmetry in the ttbar dilepton channel has been performed at the LHC proton-proton collision energy of 7 TeV. This measurement has been realized for a total integrated luminosity of 5.0/fb , corresponding to the dilepton data set collected during the year 2011 by the CMS experiment. The inclusive asymmetry has been measured to be 0.050+-0.043(stat)+0.010-0.039(syst). The measurement is also given in a differential form, as a function of the invariant mass, the transverse momenta and the rapidity of the ttbar system. In addition, the inclusive charge asymmetry based on the lepton rapidities is measured to be 0.010+-0.015+-0.006. All measurements are consistent with their stardard model expectations.

Approved Results from TOP-12-010

Figure / Table Abbreviated Caption
Estimate of the W+jet like and QCD like background for the three channels.

Selection efficiency (fraction of number selected events to number of generated events) as estimated in our analysis and used in the unfolding procedure for the sensitive variable.

Selection efficiency (fraction of number selected events to number of generated events) as estimated in our analysis and used in the unfolding procedure for the sensitive variable over the invariant mass of top pair system.

Migration matrix as estimated in our analysis and used in the unfolding procedure for the sensitive variable.

Migration matrix as estimated in our analysis and used in the unfolding procedure for the sensitive variable over the invariant mass of the top pair system.

Unfolded results compared to theoretical predictions. Inclusive measurement.

Unfolded results compared to theoretical predictions. Differential asymmetry in the invariant mass of the top pair system.

Unfolded results compared to theoretical predictions. Differential asymmetry in the rapidity of the top pair system.

Unfolded results compared to theoretical predictions. Differential asymmetry in the transverse momenta of the top pair system.

Background-subtracted and unfolded asymmetry distributions for the leptonic charge asymmetry. The error bars represent statistical uncertainties only, while the systematic uncertainty band is represented by the hatched area. Note that the bin values are correlated due to the unfolding.

Background-subtracted and unfolded asymmetry distributions for the top forward-backward asymmetry. The error bars represent statistical uncertainties only, while the systematic uncertainty band is represented by the hatched area. Note that the bin values are correlated due to the unfolding.

Dependence of the unfolded top forward-backward asymmetry on the invariant mass of the top pair system.

Summary of the unfolded asymmetries and invariant mass of the top pair system dependence of the unfolded top forward-backward asymmetry. The uncertainties on the data results include both statistical and systematic uncertainties. The uncertainties on the POWHEG results are only statistical.
Topic attachments
I Attachment History Action Size Date Who Comment
PNGpng 1dclassyunfold_unfolded.png r1 manage 55.7 K 2012-11-09 - 12:25 MarcoCardaci  
PNGpng 1dmigmatrix_m.png r1 manage 48.8 K 2012-11-09 - 12:43 MarcoCardaci  
PNGpng 1dseleff_1dplot.png r1 manage 31.6 K 2012-11-09 - 12:43 MarcoCardaci  
PNGpng AfbVsMtt_unfolded_top_costheta_cms.png r1 manage 64.6 K 2012-11-09 - 12:45 MarcoCardaci  
PNGpng MatrixMethod.png r1 manage 52.0 K 2012-11-09 - 12:46 MarcoCardaci  
PNGpng Results.png r1 manage 131.7 K 2012-11-09 - 12:46 MarcoCardaci  
PNGpng classyunfold_diffvis_m.png r1 manage 51.3 K 2012-11-09 - 12:41 MarcoCardaci  
PNGpng classyunfold_diffvis_pt.png r1 manage 47.4 K 2012-11-09 - 12:42 MarcoCardaci  
PNGpng classyunfold_diffvis_y.png r1 manage 43.5 K 2012-11-09 - 12:42 MarcoCardaci  
PNGpng finalplot_unfolded_lep_charge_asymmetry.png r1 manage 73.6 K 2012-11-09 - 12:45 MarcoCardaci  
PNGpng finalplot_unfolded_top_costheta_cms.png r1 manage 96.9 K 2012-11-09 - 12:45 MarcoCardaci  
PNGpng migmatrix_m.png r1 manage 82.3 K 2012-11-09 - 12:44 MarcoCardaci  
PNGpng seleff_m.png r1 manage 62.5 K 2012-11-09 - 12:44 MarcoCardaci  
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Topic revision: r2 - 2012-11-09 - RobertoTenchini
 
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