标题： 味道和水平对称性 显示英文标题

标题： Flavors and Horizontal Symmetries

摘要： 在简要介绍了需要解决的基本味问题之后，我介绍了水平对称性的基本思想，其群为$G_H$。 为了具体模型构建的目的，根据$G_H$被打破的尺度对模型进行分类是有用的。 我考虑了三种情况：低于$m_t$；稍微高于$m_t$；以及在$M_{GUT}$处。 在讨论了$E_6 \times E_8'$超弦中的影子扇区之后，有一个总结。 显示英文摘要

摘要： After a brief introduction to what are the basic flavor questions to be addressed, I introduce the underlying ideas of horizontal symmetries, with group $G_H$. For the purposes of specific model building, it is useful to classify models according to the scale at which $G_H$ is broken. I consider the three cases: below $m_t$; somewhat above $m_t$; and at $M_{GUT}$. After a discussion of the shadow sector in the $E_6 \times E_8'$ superstring, there is a summary.