Date of Award

Spring 5-20-2024

Document Type

Undergraduate Honors Thesis

Degree Name

Bachelor of Science in Physics




Dr. Chad Kishimoto


The early universe provides a unique opportunity for researching neutrinos because in these dense and hot places, neutrinos have significant interactions with each other and everything else in the plasma of the early universe. One issue in the current cosmological paradigm is the lithium problem, where there is a discrepancy between predicted versus observed abundances of lithium produced during Big Bang Nucleosynthesis. In this paper, we look beyond the Standard Model to try and address this discrepancy by using the early universe as a laboratory to study the decay of sterile neutrinos into Standard model particles and its effect on cosmological observables. These decays create nonthermal neutrino spectra as opposed to nearly thermal spectra predicted by standard cosmology. These altered spectra affect the production of primordial elements during BBN and the formation of large scale structure.