  Spectroscopy of family gauge bosons is investigated based on a U(3) family
gauge boson model proposed by Sumino. In his model, the family gauge bosons are
in mass eigenstates in a diagonal basis of the charged lepton mass matrix.
Therefore, the family numbers are defined by $(e_1,e_2, e_3)=(e, \mu, \tau)$,
while the assignment for quark sector are free. For possible family-number
assignments $(q_1, q_2, q_3)$, under a constraint from $K^0$-$\bar{K}^0$
mixing, we investigate possibilities of new physics, e.g. production of the
lightest family gauge boson at the LHC, $\mu^- N \rightarrow e^- N$, rare $K$
and $B$ decays, and so on.
