New Physics at the Neutrino Oscillation Frontier

Abstract

The discovery of neutrino oscillations implies that neutrinos are massive, and therefore is a concrete evidence that the standard model (SM), which forbids the mass of neutrinos, is not complete. As a consequence, completing the knowledge of neutrino oscillations extends our understanding of new physics. We are entering the age of precision measurement of neutrino oscillations, with the preparation for the upcoming Long Baseline experiments (LBL) — Deep Underground Neutrino Experiment (DUNE) and Tokai to Hyper-Kamiokande (T2HK). In this thesis, we firstly study how DUNE, T2HK and the combination solve the remaining problems of the standard neutrino oscillation — octant and mass ordering degeneracy problems, if CP violates, and what the value of CP phase is. In the following, we study how Littlest Seesaw Models (LS) can be tested by DUNE, T2HK together with short- and medium-baseline reactor experiments, after fitting these models with the current global results. In the next half of this thesis, we extend our discussion to allow external interactions — nonstandard interactions (NSIs) in matter for DUNE. After reviewing current studies on the precision of NSI-parameter measurement, we discuss the exclusion ability of DUNE to the SM prediction over the possible scenarios. Considering NSIs are flavour-dependent, we demonstrate the possible correlations between or among NSI effects under flavour symmetries A4 and Z2. Based on these correlations, we present how DUNE can test flavour symmetries A4 and Z2 through NSIs. Our results show the experimental properties of DUNE and T2HK, and how they perform for the theory of flavour symmetry.