Electroweak Physics at the Large Hadron Collider with the ATLAS Detector

This thesis discusses searches for electroweakly produced supersymmetric partners of the gauge and the Higgs bosons (gauginos and higgsinos) decaying to multiple leptons, using pp collisions at sqrt(s) = 13 TeV. The thesis presents an in-depth study of multiple searches, as well as the first 13 TeV cross section measurement for the dominant background in these searches, WZ production. Two searches were performed using 36.1/fb of data: the gaugino search, which makes use of a novel kinematic variable, and the higgsino search, which produced the first higgsino limits at the LHC. A search using 139/fb of data makes use of a new technique developed in this thesis to cross check an excess of data above the background expectation in a search using a Recursive Jigsaw Reconstruction technique. None of the searches showed a significant excess of data, and limits were expanded with respect to previous results. These searches will benefit from the addition of luminosity during HL-LHC; however, the current detector will not be able to withstand the increase in radiation. Electronics for the detector upgrade are tested and irradiated to ensure their performance.

Autorentext
Elodie received a B.S. in electrical engineering, with a minor in physics, from the University of California, Davis in 2014, and a Ph.D. in physics from the University of Pennsylvania in 2019. Elodie is currently a Chamberlain postdoctoral fellow at Lawrence Berkeley National Laboratory working on the ATLAS experiment.

Inhalt
Introduction.- Theoretical Framework.- LHC and the ATLAS Detector.- HL-LHC Inner Detector Upgrade.- W±Z Cross-Section Measurement at ps = 13 TeV.- Searches for Electroweak SUSY: Motivation and Models.- Search for wino-bino production decaying via WZ at ps = 13 TeV.