Search for a heavy scalar boson in the $Z Z \rightarrow l^{+} l^{−} \nu\bar{\nu}$ decay channel and reconstruction of high-energy muons in the CMS experiment

The following thesis is organized as fallow. The first chapter introduces the phe- nomenology of the Standard Model and describes some aspects of the 2HDM and it finishes with a short description of the latest results obtained in CMS in the scalar sec- tor. The second chapter is dedicated to the description of the two main instruments of the analysis: the Large Hadron Collider (LHC) and the Compact Muon Solenoid (CMS). The description of how the particles and more complex objects, like the jets and the Missing Transverse Energy, are reconstructed and identified is the main topic of the third chapter. The last two chapters are dedicated completely to describe the work and the results of the PhD thesis. The chapter four describes the search of a new heavy scalar resonance in the ZZ → 2l2ν channel. The work was shared with the "Université Libre de Bruxelles", the "University of Delhi", and "Beihang University". The final results are used to set limits on the cross section of the generic heavy scalar resonance in the ZZ channel combing the results with the ZZ → 4l and ZZ → 2l2q results. Finally, the last chapter is totally dedicated to describe the strategies adopted by the CMS collaboration to reconstruct muons with transverse momentum greater then 300 GeV focusing in particular on the Dynamic Truncation Algorithm and its performances.