Yukawaon Model with U(3)$\times$O(3) Family Symmetries

Abstract

A quark and lepton mass matrix model with family symmetries U(3)$\times$O(3) is investigated on the basis of the so-called yukawaon model. In the present model, quarks and leptons are assigned to $(\ell, e^c, u^c) \sim ({\bf 3}, {\bf 3}, {\bf 3}^*)$ of U(3) and $(q, d^c, ν^c) \sim ({\bf 3}, {\bf 3}, {\bf 3})$ of O(3). Then, the neutrino mass matrix is given by $M_ν= m_D M_R^{-1} m_D^T$ with $m_D \propto < Φ_e > $, where the charged lepton mass matrix $M_e$ is given by $M_e = k < Φ_e ><Φ_e^T >$. A merit in considering U(3)$\times$O(3) lies in that we can lower the cutoff scale $Λ$ in the yukawaon model.

14 pages, no figure, minor change of model, title changed