Date of Award
Summer 2025
Document Type
Open Access Dissertation
Department
Physics and Astronomy
First Advisor
Brett Altschul
Abstract
Symmetries in atomic, electromagnetic, and weak interaction physics are explored to understand symmetry-breaking extensions of the Standard Model of particle physics. Lorentz-violating field theories are extremely interesting theoretically, since they possess many new features that are absent in Lorentz-invariant models. We outline the formalism and experimental status of the Lorentz- and CPT-violating Standard Model Extension, in both the classical and quantum regimes. Processes such as vacuum Cerenkov radiation, which are kinematically forbidden when Lorentz symmetry is exact may become allowed when this symmetry is weakly broken. Particle decays, such as pion and kaon decays, although allowed in Lorentz-invariant theories, are also used as tools to probe Lorentz violation. For example, in pion decay, it is possible to have Lorentz violation in both the $W$-boson and muon sectors. We look at two separate sectors of the extended theory, with preferred axial-vector and tensor backgrounds, respectively.
Following introductory remarks, the general framework for models of extending Standard Model physics to account for possible Lorentz violation is laid out. Experimental bounds are given for the Lorentz-violating parameters used in our work, along with a few others for comparisons to other types of models that could be worked on in similar future analyses. In our first model, we analyze a modification to electromagnetism involving vacuum-birefringence effects in the photon sector, by searching for symmetry-breaking in the classical Larmor radiation formula. For the second analysis, we analyze a three-particle decay process with Lorentz symmetry broken in each of the three outgoing particle's energy-momentum relation. We obtain new decays rates and Dalitz plot outlines. The analysis of possible extensions of this type of work in future research is discussed, including how precision measurements could be of use in constraining the Lorentz violation coefficients for spinless three-particle decay processes.
Rights
© 2025, Joshua Martin O'Connor
Recommended Citation
O'Connor, J. M.(2025). The Role of Symmetries in Atomic, Electromagnetic, and Particle Physics. (Doctoral dissertation). Retrieved from https://scholarcommons.sc.edu/etd/8516