Measurements of single, double and triple differential cross-sections of top-quark pair production, in the lepton+jets channel, in pp collisions at Ös=13 TeV using the data collected by the ATLAS detector during the full Run 2.

Abstract

In this thesis the differential cross-sections for the inclusive production of t t pairs have been measured at a center-of-mass energy of p s = 13 TeV. The data were collected by the ATLAS detector during the period spanning from 2015 to 2018, also known as Run 2, and correspond to an integrated luminosity of 140 fb􀀀1. The top-quark pair events were selected in the lepton (either electron or muon) plus jets channel. The single, double and triple differential cross-sections have been measured as a function of the kinematic variables of the t t system or the hadronically decaying top-quark and extrapolated to the full phase-space. The large amount of t t pairs produced at LHC gives the opportunity to perform stringent tests of pQCD by comparing the measured spectra with the theoretical fixed-order NNLO and Monte Carlo predictions.