Study of top quark processes and L1 trigger in the Run 3 of the LHC

This doctoral thesis in experimental high-energy physics, conducted at CERN using data from the CMS experiment at the LHC, focuses on the analysis of particle production mechanisms in proton-proton collisions. It presents precise measurements of the production cross section of top quark-antiquark pairs with W bosons (ttW), using data from 2016–2018 at 13 TeV, yielding the most accurate results to date within the Standard Model. Differential cross sections were also measured to better understand key observables in the modeling of the ttW process. Additionally, the thesis reports on the production of W and Z bosons (WZ) in a cleaner using 2022 data, achieving a record 3.5% precision and marking the culmination of 15 years of WZ studies at the LHC. Beyond data analysis, the work contributes to CMS detector operations by studying aging effects in the drift tube system and ensuring its efficiency under HL-LHC conditions. It also introduces a new real-time algorithm to trigger events based on the signatures of high transverse momentum muons by exploiting electromagnetic shower signatures in the Drift Tubes systems of CMS, enhancing trigger capabilities for the future High Luminosity LHC.