Sébastien Rettie

My research interests lie in the area of experimental high-energy particle physics, which studies the fundamental building blocks of the universe and their interactions with each other. More precisely, I am a member of the ATLAS Experiment at the Large Hadron Collider (LHC) at CERN.

After the discovery of the Higgs boson in 2012, the next logical step of the physics program at the LHC is to precisely measure the properties of this particle. To this end, I am working on measuring the properties of the Higgs boson, which may provide hints of new physics in regions of phase space that have yet to be fully explored. I am also investigating the use of machine learning techniques to improve the b-tagging and tracking capabilities of the ATLAS detector, and have served as the convener of the Clustering and Tracking In Dense Environments group.

During my undergraduate and graduate studies, I searched for physics beyond the standard model. Particularly, I worked with the ATLAS supersymmetry group as an undergraduate research assistant, and actively contributed to the Z' search efforts at the LHC during my graduate studies under the supervision of Oliver Stelzer-Chilton. The specific signature I looked for during my Ph.D. was that of a Z' candidate decaying into two leptons (either two electrons or two muons) in the final state. In addition, I served as the liaison between the ATLAS Exotics and the Muon Combined Performance groups. In order to gain hardware experience, I was part of the group aiming to characterize small-strip Thin Gap Chambers for the New Small Wheel upgrade of the ATLAS detector. I also contributed to the muon trigger group as an editor of the full Run 2 publication, and evaluated the performance of the ATLAS detector by measuring muon trigger efficiencies for high-momentum muons. My dissertation can be found here.