Measurement of Charge Asymmetry in Top Quark Pair Production at the Large Hadron Collider

We present a measurement of charge asymmetry in the production of top and antitop quark pairs in proton-proton collisions, in a sample of $19.6\mathrm{fb}^{-1}$ of data collected by the CMS experiment at 8 TeV center of mass energy in 2012. Selected events have a single isolated electron or muon, and at least four jets, at least one of which is likely due to a bottom quark. A template technique is employed to measure top-antitop asymmetry in two kinematic observables simultaneously, which allows attribution of contributions to the observed forward-central asymmetry from distinct Standard Model production mechanisms. An asymmetry $A_c^y=(0.15\pm0.42)\%$ is measured in the difference of absolute rapidities of top-antitop pairs, of which $(0.00\pm0.43)\%$ is attributable to quark-antiquark initial states, and $(0.18\pm0.15)\%$ is attributable to quark-gluon initial states. The first measurement of the transverse top quark charge asymmetry is also presented, with the result $A_c^\phi=(0.44\pm0.50)\%$. Measurements of the inclusive asymmetry on selections with high and low top system mass and absolute rapidity are consistent with the main result. The results are compared to Standard Model predictions and measurements from the LHC and the Tevatron.