In the four-dimensional effective theory from string compactification discrete flavor symmetries arise from symmetric structure of the compactified space and generally contain both the R symmetry and non-R symmetry. We point out that a new type of non-Abelian flavor symmetry can also appear if the compact space is non-commutative. Introducing the dihedral group D_4 as such a new type of flavor symmetry together with the R symmetry and non-R symmetry in SU(6)×SU(2)_R model, we explain not only fermion mass hierarchies but also hierarchical energy scales including the breaking scale of the GUT-type gauge symmetry, intermediate Majorana masses of R-handed neutrinos and the scale of μ-term.
雑誌名
Progress of theoretical physics
巻
106
号
6
ページ
1275 - 1295
発行年
2001
出版者
理論物理学刊行会
ISSN
0033-068X
書誌情報
Progress of theoretical physics. 2001, 106(6), p. 1275-1295.