  Gauge field theory of a horizontal symmetry of the group G = SU(2) X U(1) is
developed so as to generalize the standard model of particle physics. All
fermion and scalar fields are assumed to belong to doublets and singlets of the
group in high energy regime. Mass matrices with four texture zeros of Dirac and
Majorana types are systematically derived. In addition to seven scalar
particles, the theory predicts existence of one peculiar vector particle which
seems to play important roles in astrophysics and particle physics.
