PHENOMENOLOGICAL TOPICS IN NEUTRINO PHYSICS

Abstract

At the present stage of particle physics, one of those few windows with solid experimental evidences to new physics beyond the Standard Model is in neutrino physics. Although it has been about one century since Pauli’s proposal of neutrino in 1930, we are still far from a genuine understanding on these mysterious particles. In this Thesis, I focus on several phenomenological topics in neutrino physics. The first topic is on the Dirac/Majorana nature of massive neutrinos, in which the status of Majorana CP-violating phases in neutrino oscillations is discussed both in the context of conventional quantum mechanics and in the context of PT-symmetric non-Hermitian quantum mechanics. The second topic is on the sufficient and necessary conditions for CP-conservation with Majorana neutrinos, in which the corresponding weak-basis invariants are utilised in the construction of conditions. The third topic is on the identification of “flavour eigenstates” in the PT-symmetric non-Hermitian neutrino oscillations. The fourth topic is on an experimentally favoured μ−τ symmetry in the canonical seesaw mechanism and its implications. The last part is devoted to a neutrino mass generation mechanism based on the negative kinetic term and a combination of Higgs doublet and Higgs singlet. Relevant backgrounds are introduced accordingly.