Measuring the production of three massive vector bosons in the four-lepton channel in pp collisions at √s= 13 TeV with the ATLAS experiment at the LHC

Abstract

The Standard Model (SM) of particle physics, while describing fundamental matter constituents and their interactions, remains incomplete. By examining the production of three massive vector bosons, we can directly investigate the non-Abelian gauge structure of the SM electroweak sector, probing the SM triple and quartic gauge couplings. Deviations from the expected values in these rare processes might offer clues to new physics phenomena. This dissertation measures the production of three massive vector bosons (WWZ, WZZ, and ZZZ), focusing on events with four reconstructed leptons. The study uses 140 fb⁻¹ of proton-proton collisions at √s = 13 TeV with the ATLAS detector at the Large Hadron Collider. Machine learning is employed to distinguish signal from background events and increase the statistical significance.