  The existence of the dark matter with amount about five times the ordinary
matter is now well established experimentally. There are now many candidates
for this dark matter. However, dark matter could be just like the ordinary
matter in a parallel universe. If both universes are described by a non-abelian
gauge symmetries, then there will be no kinetic mixing between the ordinary
photon and the dark photon, and the dark proton, dark electron and the
corresponding dark nuclei, belonging to the parallel universe, will be stable.
If the strong coupling constant, $(\alpha_s)_{dark}$ in the parallel universe
is five times that of $\alpha_s$, then the dark proton will be about five time
heavier, explaining why the dark matter is five times the ordinary matter.
However, the two sectors will still interact via the Higgs boson of the two
sectors. This will lead to the existence of a second light Higss boson, just
like the Standard Model Higgs boson. This gives rise to the invisible decay
modes of the Higgs boson which can be tested at the LHC, and the proposed ILC.
