Dimension-8 EFT effects in the WZ background in the ssWW EFT fit

In search of new physics (BSM), one focus at the LHC is vector boson scattering such as the process of same charge 𝑊±𝑊± (ssWW) scattering. The quartic gauge couplings contributing to the process allow studies on electroweak symmetry breaking and are sensitive to possible effects of new physics. Effective field theories (EFT) are a way to quantify these BSM effects by extending the Standard Model (SM) Lagrangian by operators of higher energy dimension. The dimension-8 EFT operators are the lowest order operators only generating quartic gauge vertices, and so far, only the signal process ssWW scattering itself was considered when searching for unitarity limits of these dimension-8 operators. This thesis works with ssWW EFT samples as well as with WZ EFT samples based on Run 2 measurements of 138.7 fb$^{-1}$ at ATLAS. $\pm1\sigma$, $\pm2\sigma$ limits for the coeffcients of each operator at different clipping values of the center of mass energy of the ssWW process are extracted using either ssWW EFT samples only or WZ EFT samples or both at once. A value of maximum validity for each operator is obtained by comparing theoretical unitarity bounds with the limits found. This procedure is done in the ssWW signal region, and for the WZ EFT samples repeated in a WZ control region.