Measurements of differential cross sections for the production of top quark pairs in pp collisions at $\sqrt{s} = 13$ TeV with the CMS experiment

In this thesis, measurements of differential cross sections of top quark pair ($t\bar{t}$) production in proton-proton (pp) collisions at $\sqrt{s}=13 \text{ TeV}$ are presented. The analysis is based on data obtained with the CMS experiment during 2016, 2017 and 2018 in Run 2 of the LHC, which corresponds to an integrated luminosity of 137.6 fb$^[-1]$. In this period of time more than 100 million $t\bar{t}$ pairs were produced in the pp collisions, facilitating an unprecedented precision in measurements of kinematic spectra and topologies in these events. The analysis is performed using the dileptonic decay channel. Differential $t\bar{t}$ production cross sections are measured in bins of the kinematic properties of the $t\bar{t}$ system, the top quarks and their visible decay products, the charged leptons and beauty flavoured jets. The cross section extraction is based on an event-counting method using reconstructed distributions, where detector effects such as resolutions, acceptances and efficiencies are corrected through a regularized unfolding procedure. The measurements are presented in the full phase-space at parton level and/or in the fiducial phase space at particle level. Both absolute and normalized cross sections are provided. All measurements are compared to alternative MC predictions based on next-to-leading order (NLO) QCD models matched to parton showers and some selected results are also compared to theoretical predictions beyond NLO precision in QCD. Most cross sections are measured single-differentially as functions of one kinematic observable, but also some double-differential cross sections are extracted as functions of two observables.