The Tri-Bimaximal Neutrino Mixing Matrix Could Be Modified By Adding Sterile Neutrinos

• Main Authors: Feng, Tzu-Yun, 馮子耘
• Other Authors: Cheung, Kingman
• Format: Others
• Language: en_US
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/90153712667088276500

碩士 === 國立清華大學 === 物理系 === 103 === The phenomenon of neutrino oscillation has been established. It implies that neutrinos having masses, so the mass eigenstate is different with the flavor eigenstate. They has mixing matrix described by a 3 × 3 unitary matrix, PMNS, like CKM matrix in quark sector. The most famous pattern is Tri-Bimaximal mixing matrix which predicts a vanishing θ13, but we have experimental evidence for a non vanishing value of the smallest θ13. TriBimaximal mixing matrix needs modifications. We study discrete flavour symmetries model(A4 symmetry), higher symmetry model and sterile neutrinos to explain small angle. First, suppose there has A4 symmetry or higher symmetry in lepton sector and neutrino sector and neutrinos have Majorana masses(or only have Dirac neutrinos). We will get Tri-Bimaximal mixing in A4 model. Second, Adding sterile neutrinos modify the mixing matrix, therefore we could get small angle(θ13). Then, transforming with new mixing matrix, we found ranges of neutrino masses,mixing angle and so on. We compare them to the experiment data