A search for flavor-changing neutral current interactions in leptonic final states using the CMS detector
Embargo Date
2025-09-17
OA Version
Citation
Abstract
The Large Hadron Collider (LHC) is the world’s largest particle accelerator. In 2012, the LHC announced that a new particle had been observed with data collected from its two major experiments, including the Compact Muon Solenoid (CMS). Since then, particle physicists have studied this new particle extensively and determined that it has the properties of the Higgs Boson. We are now in an era of particle physics where the Higgs boson can be used to probe theories of physics beyond the Standard Model (BSM). In this thesis, I am using it to search for flavor-changing neutral current (FCNC) interactions, where the Higgs Boson plays the role of the neutral mediator of a quark flavor-change. These processes are greatly suppressed in the Standard Model but could be enhanced by several theories beyond the SM. The Standard Model predicted cross section for these interactions is on the order of 10^(−15) fb, which is too rare to be observed with the LHC. This means that any observance of FCNC interactions would be evidence of BSM physics. The presented analysis sets upper limits on the coupling constant of the top quark, Higgs Boson, and either an up or a charm quark, using data collected at CMS during 2016-2018. In this thesis, I will present my search for FCNC in leptonic final states, which utilizes robust, data-driven background estimation methods and multivariate techniques to improve our results.