́Etude des états finals à deux bosons Z dans le canal leptons-neutrinos dans l'expérience CMS auprès du LHC au CERN

This thesis presents a study of ZZ final states performed with data recorded with the CMS detector. This study exploits the first data delivered by the LHC and recorded by CMS in 2010 and 2011. The ZZ production cross section is measured and limits are set on neutral electroweak triple gauge couplings. The existence of such couplings would be an indication of new physics beyond the Standard Model. Moreover, the ZZ process in the Standard Model is a background for Higgs searches and have to be well known. Some preliminary studies are performed on the CMS electromagnetic calorimeter. These studies are related to the selective readout system and to the laser monitoring system of the electromagnetic calorimeter. The measurement and the behaviour of the transverse missing energy are also studied in events containing one electroweak boson decaying into electron(s). This study shows that pileup has a important effect on missing transverse energy measurements. Some corrections have to be taken into account to deal with these effects. Conclusions from these analyses contribute to the good understanding of results obtained in the ZZ final states study.