  A Schwinger boson mean field theory is developed for spin liquids in a
symmetric spin-orbital model in higher dimensions. Spin, orbital and coupled
spin-orbital operators are treated equally. We evaluate the dynamic correlation
functions and collective excitations spectra. As the collective excitations
have a finite energy gap, we conclude that the ground state is a spin-orbital
liquid with a two-fold degeneracy, which breaks the discrete spin-orbital
symmetry. Possible relevence of this spin liquid state to several realistic
systems, such as CaV$_4$V$_9$ and Na$_2$Sb$_2$Ti$_2$O, are discussed.
