  Recent theoretical calculations and experimental results suggest that the
strongly correlated material SmB$_{6}$ may be a realization of a topological
Kondo insulator. We have performed an angle-resolved photoemission spectroscopy
study on SmB$_{6}$ in order to elucidate elements of the electronic structure
relevant to the possible occurrence of a topological Kondo insulator state. The
obtained electronic structure in the whole three-dimensional momentum space
reveals one electron-like 5d bulk band centred at the X point of the bulk
Brillouin zone that is hybridized with strongly correlated f electrons, as well
as the opening of a Kondo bandgap ($\Delta_B$ $\sim$ 20 meV) at low
temperature. In addition, we observe electron-like bands forming three Fermi
surfaces at the center $\bar{\Gamma}$ point and boundary $\bar{X}$ point of the
surface Brillouin zone. These bands are not expected from calculations of the
bulk electronic structure, and their observed dispersion characteristics are
consistent with surface states. Our results suggest that the unusual
low-temperature transport behavior of SmB$_{6}$ is likely to be related to the
pronounced surface states sitting inside the band hybridisation gap and/or the
presence of a topological Kondo insulating state.
