2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/46952A seesaw mass matrix model is reviewed as a unification model of quark and lepton mass matrices. The model can understand why top-quark mass m_t is so singularly enhanced compared with other quark masses, especially, why m_t >> m_b in contrast to m_u = O(m_d), and why only top-quark mass is of the order of the electroweak scale Lambda_W, i.e., m_t = O(Lambda_W). The model predicts the fourth up-quark t' with a mass m_{t'}= O(m_{W_R}), and an abnormal structure of the right-handed up-quark mixing matrix U_R^u. Possible new physics is discussed.talk at MMQL97. 11 pages (including a figure) [Latex]High Energy Physics - Phenomenologytext