Non-Abelian discrete flavor symmetries from modular symmetry in string compactification
卓也 立石 · Hokkaido University Collection of Scholarly and Academic Papers (Hokkaido University) · 2019
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.