open access

https://doi.org/10.14943/doctoral.k13564

https://hdl.handle.net/2115/74294

超弦理論におけるモジュラー対称性由来の非可換離散フレーバー対称性に関する研究

英語

2019-03-25

Hokkaido University

iv, 62p.

Modular symmetry is a symmetry on two dimensional torus T2 typically considered in string compacti cation. First, we study the modular symmetry in magnetized D-brane models on T2. Zero-modes on T2 with magnetic flux M= 2 (in a certain unit) are transformed as doublet of S3 with certain identi cation under the transformation of the modulus. We also study the modular symmetry in heterotic orbifold models. The T2/Z4 orbifold model has the same modular symmetry as the magnetized D-brane model with M= 2. Next, we study lepton flavor models with S3 and A4 symmetries from the modular group. We consider S3 model with flavons and A4 models with no flavon. In A4 model, we classify our neutrino models along with typeI seesaw model, Weinberg operator model, and the Dirac neutrino model.In the normal hierarchy of neutrino masses, the seesaw model is available by taking account for recent experimental data of neutrino oscillations. In the case of inverted hierarchy, the Dirac neutrino model is consistent with experimental data.

2019-03-25

甲第13564号

博士(理学)

(主査) 教授 小林 達夫, 教授 鈴木 久男, 准教授 中山 隆一, 特任准教授 瀬戸 治

理学院（宇宙理学専攻）

博士論文

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