Inclusive and differential cross-section measurements of tW single top-quark production at √s = 13 TeV with the ATLAS detector

Abstract

This thesis presents the inclusive cross-section measurement and so far the first differential cross-section measurement for the associated production of a top quark and a W boson, known as the tW-channel, at 13TeV. The dataset corresponds to an integrated luminosity of 36.1/fb, collected by the ATLAS detector at the LHC in 2015 and 2016. The inclusive cross-section is measured to be 71 ± 2 (stat.)+12 (syst.) ± 3 (lumi.) pb, which agrees with the theoretical prediction, indicating no new physics observed. Furthermore, a tW enriched region is selected and the differential cross-section is measured for several particle-level observables. Six observables are chosen, constructed from the masses and energies of leptons and jets as well as the transverse momenta of neutrinos. Measurements are normalised with the fiducial cross-section. Results are found to be in good agreement with predictions from several Monte Carlo event generators.