Search for Supersymmetry in Leptonic Final States with the CMS Detector

Abstract

This dissertation describes a number of searches for yet undiscovered particles predicted by theories beyond the standard model of particle physics. The searches have been carried out with 35.9 fb$^{-1}$ of proton-proton collision data at an unprecedented center-of-mass energy of sqrt(s) = 13 TeV, recorded in 2016 by the CMS experiment at the CERN LHC. New particles are assumed to be produced either via the strong or the electroweak interaction in the scope of the minimally supersymmetric standard model. In this document, the examined final states either contain a pair of electrons or muons of the same electric charge or more than two leptons, also including hadronic tau lepton decays. As known standard model processes are expected to contribute at low rate to either of these final states, the searches are sensitive to possible new physics phenomena. The dissertation includes a general introduction to the theoretical and experimental setup, followed by an extensive review of the search strategy and estimation of background processes. Results of the analyses are presented as comparisons of observed to predicted number of events in dedicated search regions, and are interpreted in the scope of the supersymmetric models. The results obtained in the search for electroweak superparticle production are combined with those from other searches carried out at CMS in 2016. Supersymmetric particles produced via the strong interaction are excluded up to masses of 1.6 TeV, which is compatible to what has been achieved by other searches conducted at CMS and ATLAS in the same period of time. The obtained results pose the most stringent limit on electroweak superpartner production mechanisms to date, ranging between 500 GeV and 1.1 TeV depending on the model