The differential cross section of top-quark-pair events is measured as a function of the number of jets in data recorded in 2012 by the CMS experiment. The proton-proton collision events analysed in this thesis were delivered by the LHC at a center-of-mass energy of 8 TeV. This measurement provides a test of the standard model and comparisons with predictions from simulation tools at leading-order and next-to-leading order of the perturbation theory are performed
