Juan Cristóbal Rivera Vergara

Topic

Estimation of Standard Model Effective Field Theory parameters in WZ leptonic decays using the ATLAS Detector

Department of Physics and Astronomy

Date & location

• Wednesday, October 22, 2025
• 1:00 P.M.
• Engineering & Computer Science Building, Room 104

Examining Committee

Supervisory Committee

• Dr. Robert McPherson, Department of Physics and Astronomy, University of Victoria (Supervisor)

• Dr. Richard Keeler, Department of Physics and Astronomy, UVic (Member)

• Dr. Isabel Trigger, Department of Physics and Astronomy, UVic (Member)

• Dr. Cornelia Bohne, Department of Chemistry, UVic (Outside Member)

External Examiner

• Dr. Heather Logan, Department of Physics, Carleton University

Chair of Oral Examination

• Dr. LJ Slovin, School of Child and Youth Care, UVic

Abstract

The discovery of the Higgs boson in 2012 became the last missing piece to complete the puzzle of the Standard Model. While able to withstand an extensive array of precision tests, the model is still unable to explain some crucial observed phenomena in the universe, such as dark matter, gravity, and baryon asymmetry. Various theories that extend the Standard Model while seeking to answer some of these questions have been proposed; among these is the Standard Model Effective Field Theory (SMEFT), that assumes the Standard Model to be an effective theory only applicable up to energies not exceeding a certain scale. This theory includes six-dimensional terms in the Lagrangian, which would affect various SM processes. The ATLAS experiment at the Large Hadron Collider was constructed to seek signs of physics beyond the Standard Model, using the data from high energy proton-proton collisions. The extra terms proposed by SMEFT would affect various processes observed in the Standard Model, resulting in small differences in kinematic and angular observables, and those differences could be measured in the events produced at ATLAS. In particular, this dissertation focuses on a set of terms that would affect the electro-weak sector of the SM, and aims to make use of angular distributions to better observe the effects on the spin and polarization of the particles. New physics is not observed, and limits are set for the values of the relevant SMEFT parameters, which were found to be consistent with SM values.