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 $(e_1,e_2, e_3)=(e, ��, ��)$, 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, $��^- N \rightarrow e^- N$, rare $K$ and $B$ decays, and so on.

15 pages. 1 figure. accepted to PLB. arXiv admin note: text overlap with arXiv:1146374