The Observation of Photon-Induced WW Production and Studies of Electron Identification with the ATLAS Experiment

This thesis presents the observation of photon-induced W + W − production using proton-proton collision data, with a centre-of-mass energy of 13 TeV and an integrated luminosity of 139 fb −1 , recorded by the ATLAS detector. Particular emphasis is given on the determination of the exclusivity scale factor used to correct the theoretical prediction of elastic production to the full photon-induced process, including dissociative production
and losses due to secondary scatterings. Further studies into the charged particle multiplicity of other multi-lepton final states are also presented, as a means to validate the background estimate. Finally, an outlook using the photon-induced WW process to set limits on effective field theory operators are given.

Furthermore, studies on electron identification in the ATLAS experiment are presented. The likelihood-based method, used to distinguish between prompt and non-prompt electrons, is altered to include information from two sources of non-prompt background electrons in an effort to improve the rejection of background electrons.