SM and EFT interpretation of Vector Boson Scattering measurements at CMS and development of the DAQ system for the Barrel Timing Layer for HL-LHC

This comprehensive work presents the culmination of a three-year research activity spanningthree key domains.The foremost focus of this research has been the search for new physics effects in VBS processes with the Effective Field Theory (EFT) approach. To fulfill this purpose a novel statisticalmodel has been crafted to facilitate the interpretation and combination of EFT analyses. To date,this model has been employed in over 10 analyses conducted by the Compact Muon Solenoid(CMS) collaboration. Characterized by a global perspective, this model readily accommodatesstatistical combinations and lays a robust groundwork for future global EFT fitting within theCMS experiment. In this context, the VBS sensitivity to EFT dimension-six operators has beenevaluated through a parton-level exercise involving the combination of Vector Boson Scattering (VBS) channels and a diboson channel, simultaneously constraining 14 Wilson coefficients.These results were compared to an additional combination study involving triboson processes.The knowledge of dimension-six effects in VBS has also been deepened by studying a realworld problem, encompassing background effects and uncertainties, through the analysis ofthe VBS WV process with a semileptonic final state. Challenges arising from the intricateVBS signature, featuring 6 final-state fermions, were surmounted by devising more efficientmethods for matrix-element reweighting. The expected sensitivity to 8 Wilson coefficients wascomputed utilizing the CMS Run 2 dataset, which amounts to an integrated luminosity of 137inverse femtobarns. Notably, for a Standard Model (SM) process, limit determinations wereperformed both for individual operators (with the others set to zero) and globally, allowing allcoefficients to vary freely in a maximum likelihood fit.In anticipation of an upcoming global EFT combination for VBS channels, the logical startingpoint involves a unified interpretation based on the SM. The combination of eight VBS analyseswas executed to quantify the parameters governing vector boson production within the VBStopology. In particular, the interplay between three processes can be instrumental in the observation of two Z bosons scattering through VBS for which CMS only obtained strong evidence.On the instrumental side, particular emphasis was placed on the development of the Data Acquisition (DAQ) system for the MIP Timing Detector (MTD), which will be installed at CMSduring the high luminosity phase of the Large Hadron Collider. The finalization of the backend component necessitated a comprehensive revision of firmware and software. The softwarearchitecture was designed with modularity in mind, establishing a one-to-one relationship between hardware components and software abstractions. Successful testing of this softwareincluded communication with the chips comprising the Barrel Timing Layer (BTL) front-endelectronics. In order to streamline and optimize the forthcoming detector construction phase,a web-based Graphical User Interface was developed to facilitate interaction with less experienced users, ensuring a prompt, robust, and efficient system for characterizing assembledmodules.