U(3)-Family Nonet Higgs Boson and its Phenomenology

In a model where quark and lepton masses and family-mixings are caused not by a variety of Yukawa couplings $y_{ij}$ ($i,j=1,2,3$: family indices) with one vacuum expectation value (VEV) $v=\langle\phi_L^0\rangle_0$, but by a variety of VEV's of a U(3)-family nonet Higgs boson $\phi_L$, $v_{i}^j=\langle\phi_{L i}^{0j}\rangle_0$, with a single coupling constant, the following problems are investigated: what constraints on the Higgs potential are imposed in order to provide realistic quark and lepton mass spectra and mixings and what constraints on the Higgs boson masses are required in order to suppress unwelcome flavor-changing neutral current effects. Lower bounds of the physical Higgs boson masses of $\phi_L$ are deduced from the present experimental data and new physics from the present scenario is speculated.