Measurements of Higgs boson properties in the four-lepton channel in pp collisions at centre-of-mass energy of 13 TeV with the CMS detector

This thesis presents the measurements of Higgs boson properties in the four-lepton decay channel in proton-proton collisions at centre-of-mass energy of 13 TeV with the CMS detector. Significant improvements in many aspects of the analysis are introduced with respect to the previous reported measurements by the CMS Collaboration. My contribution is twofold, improving the electron selection efficiency measurements and leading the analysis of data recorded in 2017 as the main author. Results of the analysis of Run II data are presented for two data sets recorded in 2016 and 2017, corresponding to integrated luminosities of 35.9~$\mathrm{fb^{-1}}$ and 41.5~$\mathrm{fb^{-1}}$, respectively. The signal strength modifiers relative to the standard model prediction, the mass and decay width of the boson, differential and inclusive cross sections are measured. All results are in good agreement with standard model expectations for a Higgs boson within the uncertainties. Finally, a measurement of the signal strength modifiers on combined 77.4~$\mathrm{fb^{-1}}$ of data collected in 2016 and 2017 is also performed and is again found to be compatible with the SM predictions. New frontiers are reached as the statistical and systematical contributions to the total uncertainty on the inclusive signal strength measurement are considerably reduced and of the same size.