Measurements of t t-bar charge asymmetry using dilepton final states in pp collisions at sqrt(s) = 8 TeV

TL;DR

This paper reports measurements of the charge asymmetry in top-antitop quark pair production using dilepton final states at 8 TeV proton-proton collisions, confirming consistency with the Standard Model predictions.

Contribution

First measurement of t t-bar charge asymmetry in dilepton final states at 8 TeV with detailed unfolding to parton level.

Findings

Measured t t-bar charge asymmetry of 0.011 +/- 0.011 (stat) +/- 0.007 (syst)

Leptonic charge asymmetry of 0.003 +/- 0.006 (stat) +/- 0.003 (syst)

Results agree with Standard Model predictions

Abstract

The charge asymmetry in t t-bar events is measured using dilepton final states produced in pp collisions at the LHC at sqrt(s) = 8 TeV. The data sample, collected with the CMS detector, corresponds to an integrated luminosity of 19.5 inverse femtobarns. The measurements are performed using events with two oppositely charged leptons (electrons or muons) and two or more jets, where at least one of the jets is identified as originating from a bottom quark. The charge asymmetry is measured from differences in kinematic distributions, unfolded to the parton level, of positively and negatively charged top quarks and leptons. The t t-bar and leptonic charge asymmetries are found to be 0.011 +/- 0.011 (stat) +/- 0.007 (syst) and 0.003 +/- 0.006 (stat) +/- 0.003 (syst), respectively. These results, as well as charge asymmetry measurements made as a function of the invariant mass, rapidity, and transverse momentum of the t t-bar system, are in agreement with predictions of the standard model.