Abelian gauge symmetries in the two-Higgs-doublet model

Abstract: The two-Higgs-doublet model is a promising extension of the Standard Model of particle physics, but it contains a large number of free parameters. With the intention to constrain this freedom, the model has been studied under different symmetries. In particular, a full classification of Abelian global symmetries has been presented in 2011. However, breaking global symmetries spontaneously leads to unobserved Goldstone bosons. This thesis, however, covers a study of the two-Higgs-doublet model under local gauge symmetries, where the origin of Goldstone bosons is avoided from the beginning. In order to do this, we examine the global symmetry classification from 2011 in the context of gauge anomalies, which provides an important criterion to investigate the consistency of a gauge theory. As our main results, we find a total of thirteen anomaly-free gauge models that are presented in detail. In addition, we perform a more in-depth study of the simplest gauge model we found and demonstrate its ability to provide physical observables in agreement with experimental data using the example of the CKM matrix.