Studies of Vector Boson Scattering in the semileptonic ZV channel with the CMS detector at $\sqrt{s}$=13 TeV

This dissertation reports on the search for the vector boson scattering (VBS) in semileptonic ZV channel, where the Z boson decays to a pair of leptons (electrons or muons), and the other vector boson V (either W or Z) decays hadronically to a pair of jets, in association of two large pseudorapidity jets i.e. $ZVjj → l+l−jjjj, l = e$ or $\mu$. The search used 137 $\text{fb}^{−1}$ of proton-proton collision data collected by the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC) with center-of-mass energy ($\sqrt{s}$) of 13 TeV from 2016 to 2018. VBS is a key process in understanding the nature of electroweak symmetry breaking (EWSB) in the framework of Standard Model (SM). Studies and instrumentation done towards the future detector upgrade to the CMS experiment which will replace the current endcap Hadronic Calorimeter (HCAL) and Electromagnetic Calorimeter (ECAL) with High Granularity Calorimeter (HGCAL) during Long Shutdown 3 (LS3) are also reported. Optimal configuration of scintillator tiles coupled to silicon photomultipliers (SiPMs) in the HGCAL is measured and suggested using testbeam measurement of scintillator tiles and noise measurement of SiPMs. Prototyping of automated wrapping of scintillator tiles in Enhanced Specular Reflector (ESR) film are also discussed.