This article presents measurements of ttÂ¯ differential cross-sections in a fiducial phase-space region, using an integrated luminosity of 3.2 fb- 1of protonâproton data at a centre-of-mass energy of s=13Â TeV recorded by the ATLAS experiment at the LHC in 2015. Differential cross-sections are measured as a function of the transverse momentum and absolute rapidity of the top quark, and of the transverse momentum, absolute rapidity and invariant mass of the ttÂ¯ system. The ttÂ¯ events are selected by requiring one electron and one muon of opposite electric charge, and at least two jets, one of which must be tagged as containing a b-hadron. The measured differential cross-sections are compared to predictions of next-to-leading order generators matched to parton showers and the measurements are found to be consistent with all models within the experimental uncertainties with the exception of the Powheg-Box+ Herwig++ predictions, which differ significantly from the data in both the transverse momentum of the top quark and the mass of the ttÂ¯ system.
Aaboud, M., Aad, G., Abbott, B., Abdallah, J., Abdinov, O., Abeloos, B., et al. (2017). Measurements of top-quark pair differential cross-sections in the eÎ¼ channel in pp collisions at âs=13 TeV using the ATLAS detector. THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS, 77(5), 292 [10.1140/epjc/s10052-017-4821-x].