UC Irvine

While the Standard Model of particle physics and the $\Lambda$CDM model of cosmology have been celebrated for their explanatory prowess, many phenomena remain unexplained. In this dissertation, we explore several methods of inquiry into these enigmas. In Chapters 2 and 3, we scrutinize signals that may hint at the presence of dark matter, and develop models through which these signals can be explained. Next, in Chapter 4, we employ well developed tools such as the path integral to formulate a new method for determining time evolution in cosmology. Finally, in Chapters 5 through 7, we use precise observations of primordial light elements to constrain theories beyond both the Standard Model and $\Lambda$CDM. Together, these investigations shed light on some of the mysteries of the cosmos and will hopefully inspire future avenues of exploration.