Recherche de violation de CP dans le couplage de Yukawa du lepton tau avec la methode du vecteur polarimetrique dans les donnees du Run 2 de l'experience CMS aupres du LHC

This thesis introduces a search for charge-parity violation in the tau Yukawa coupling with the polarimetric vector method. The presented work focuses on the optimization of the sensitivity of the last measurementperformed by the CMS Collaboration with Run 2 data, to prepare the analysis of the Run 3 data. To do so, the limitations of the deployment of the polarimetric vector method are evaluated in fully hadronic and semileptonic decay modes containing a muon, with the main objective to replace the initial methods exploiting the tau visible decays only. Results from this study then motivated the possibility to perform a full analysis of Run 2 data in the a13pr+µ final state with the tau leptons pair kinematic fit algorithm GEF. An improvement of the expected sensitivity of 15% is obtained with the polarimetric vector method in comparison to previous results. Work related to the study of tau spin observables in embedded samples has also been performed. Finally, the performance of the tau decay mode identification with the HPS algorithm has been evaluatedin presence of the new photon and electron identification methods implemented within the CMS particle flow algorithm. Keywords : particle physics, CMS, LHC, Higgs boson, tau lepton, CP violation, polarimetric vector, Yukawa coupling