Analysis of the vector boson scattering in a leptonic decay channel at the LHC energies and projection for HL LHC using EFT based extensions of the standard model

Abstract

In this thesis, the study of like sign W bosons scattering in the purely leptonic final state is presented. The analysis has been done using the proton-proton collisions LHC data at a center-of-mass energy of 13 TeV. The data has been recorded by the CMS experiment during LHC full Run II and corresponds to an integrated luminosity of 137 fb inverse . The work is focused on the measurements of the anomalous quartic gauge couplings in the like sign WW scattering process. In the present work, only leptonic decays of the W bosons are being studied. Due to the newlinepresence of statistical constraints, WW scattering process is probed indirectly by measuring the anomalous quartic gauge couplings (aQGCs). The events are selected by requiring two jets with large rapidity separation and di-jet invariant mass, two like-sign leptons (electrons or muons) and missing transverse momentum . Constraints are imposed on the quartic vector boson interactions in the framework of dimension-8 effective field theory operators at 95% confidence level (CL). The validity of EFT approach is taken into consideration and the clipping method is implemented for the first time in the CMS data analysis in order to use the EFT framework in the region of its validity. Comparison of the dimension-8 limits, calculated with and without consideration of EFT validity, is also carried out. newline