Searches for new physics with tau leptons at the CMS experiment
File(s)
Author(s)
Uttley, George
Type
Thesis
Abstract
The Standard Model (SM) of particle physics is currently the best model of the fundamental particles and their interactions. However, there are significant theoretical issues and experimental tensions with the model. The theoretical issues include the hierarchy problem which forecasts the breakdown of the SM when looking at the size of corrections needed to calculate the mass of the newest found member of the theory, the Higgs boson particle. The current experimental tensions include the B anomalies and the measurement of the muon anomalous magnetic moment. Looking for signatures of theoretical explanations to these issues offers excellent search options for new fundamental particles. This thesis describes searches for new physics that can explain both the theoretical problems and experimental tensions. This is done using tau leptons seen during Run 2 of the Large Hadron Collider at the Compact Muon Solenoid (CMS) experiment. The beyond SM theories searched for range from the Minimal Supersymmetric SM (MSSM), leptoquarks, and the type X two Higgs doublet models (2HDM). Two local excesses are observed with statistical significances of approximately 3 sigma for a resonance produced via gluon fusion in the di-tau final states, at masses of 100 GeV and 1.2 TeV. Otherwise, good agreement is observed between the SM background prediction and data. Leading constraints are placed on scenarios of the MSSM phase space and limits that shrink the allowed explanation to the B anomalies are set. The type X 2HDM, as an explanation for the muon anomalous magnetic moment measurement, is fully ruled out and many mass hypotheses in the type X 2HDM are completely excluded by this thesis.
Version
Open Access
Date Issued
2023-07
Date Awarded
2023-12
Copyright Statement
Creative Commons Attribution NonCommercial NoDerivatives Licence
Advisor
Colling, David
Sponsor
Science and Technology Facilities Council (Great Britain)
Publisher Department
Physics
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)