We show that , under general assumptions , in six-dimensional brane-world models with compactified large extra dimensions , the energy density of brane oscillations scales as that of cold dark matter and its present value is compatible with observations .
Such value is obtained from the only dimensional scale in the theory , namely , the fundamental scale of gravity in six dimensions M _ { 6 } \sim 1 TeV , without any fine-tuning or the introduction of additional mass scales apart from the large size of the extra dimensions .
It has been suggested that the same kind of models could provide also the correct magnitude of the cosmological constant .
This observation can be relevant for the resolution of the cosmic coincidence problem in the brane-world scenario .