UC Riverside

Though it appears to describe the world well to at least the electroweak scale, the Standard Model is becoming increasingly inadequate: it can fit fermionic masses but offers no explanation for the observed hierarchy; it provides no mechanism for generating neutrinos mass; and lastly, but perhaps most significantly, it is absent any dark matter candidate. Myriad extentions exist that are able to accommodate these problems individually including the many models that resort to ad hoc symmetries to protect dark matter. Here, extensions are motivated by generalizations of symmetries contained in the Standard Model (such as B-L) or symmetries introduced to enhance Standard Model structure. In the first part we study generalizations of U(1) gauge extensions such a B-L and I3R. For generalized B-L, we allow families to transform differently from one another and study the resulting flavor-changing neutral current constraints. In the next project, to incorporate dark matter to the puzzle, we then implement the scotogenic mechanism to generate neutrino mass via the Type II seesaw with interesting collider signatures coming from the double charged scalar. The next extension is a U(1) family symmetry that is also a dark symmetry, in both cases coupling exclusively to right-handed objects. We then push to explore Alternative Left-Right models both individually and as low-energy subgroups of the unified trinification and quartification models. We uncover naturally emerging dark symmetries for certain breaking patterns and investigate phenomenological signatures that arise from dark matter and glueball-like states of leptonic color. Obtaining gauge coupling unification at one-loop imposes further constraints on the possible symmetry breaking patterns as well as permissible low-energy particle content.