SU(5)-Compatible Yukawaon Model

Abstract

It is investigated what constraints are imposed on the so-called yukawaon model when we regard quarks and leptons as $(\bar{\bf 5}_i+{\bf 10}_i+{\bf 1}_i)$ of SU(5) ($i=1,2,3$: index of U(3) family symmetry). In past yukawaon models, the effective Yukawa coupling constants $Y_f^{eff}$ are given by vacuum expectation values of fields $Y_f$ ("yukawaons") as $(Y_f^{eff})_{ij}= (y_f/\Lambda)<(Y_f)_{ij}>$. In order to build a model without a cutoff scale $\Lambda$, vector-like fields $(\bar{\bf 5}^i+{\bf 10}^i+{\bf 5}_i +\bar{\bf 10}_i)$ are introduced in addition to the conventional quarks and leptons. The U(3) family symmetry is broken at $<Y_f>\sim 10^{13}$ GeV.