Combination of inclusive and differential $\mathrm{t}\overline{\mathrm{t}}$ charge asymmetry measurements using ATLAS and CMS data at $\sqrt{s} =$ 7 and 8 TeV

TL;DR

This paper combines charge asymmetry measurements in top quark pair production from ATLAS and CMS at 7 and 8 TeV, finding results consistent with the Standard Model and providing more precise combined measurements.

Contribution

It presents the first combined analysis of inclusive and differential charge asymmetry measurements from ATLAS and CMS at LHC energies, improving precision and consistency with the Standard Model.

Findings

Combined measurements are consistent with Standard Model predictions.

The combined asymmetry at 7 TeV is 0.005 ± 0.007 (stat) ± 0.006 (syst).

The combined asymmetry at 8 TeV is 0.0055 ± 0.0023 (stat) ± 0.0025 (syst).

Abstract

This paper presents combinations of inclusive and differential measurements of the charge asymmetry ($A_{\mathrm{C}}$) in top quark pair ($\mathrm{t}\overline{\mathrm{t}}$) events with a lepton+jets signature by the ATLAS and CMS Collaborations, using data from LHC proton-proton collisions at centre-of-mass energies of 7 and 8 TeV corresponding to integrated luminosities of about 5 and 20 fb$^{-1}$ for each experiment, respectively. The resulting combined LHC measurements of the inclusive charge asymmetry are $A_{\mathrm{C}}^{\mathrm{LHC7}} = 0.005 \pm0.007 \text{ (stat)}\pm0.006 \text{ (syst)}$ at 7 TeV and $A_{\mathrm{C}}^{\mathrm{LHC8}} = 0.0055 \pm0.0023\text{ (stat)}\pm0.0025\text{ (syst)}$ at 8 TeV. These values, as well as the combination of $A_{\mathrm{C}}$ measurements as a function of the invariant mass of the $\mathrm{t}\overline{\mathrm{t}}$ system at 8 TeV, are consistent with the respective standard model predictions.