Heterotic string dark matter from the graviton multiplet

In the string theory framework for physics beyond the standard model the hidden sector of E8×E8 heterotic string theory and the graviton multiplet provide compelling sources for the dark matter in the universe. In the present investigation I consider the graviton multiplet as one particular dark matter source in heterotic string theory. In particular, it is pointed out that an appreciable fraction of dark matter from the graviton multiplet requires a mass generating phase transition around Tc≃108 GeV, where the symmetry partners of the graviton would evolve from an ultrahard fluid to pressureless dark matter. This indicates m≃10 MeV for the massive components of the graviton multiplet, and it is reassuring that the corresponding dilaton lifetime τ≃1017 s is compatible with a dark matter interpretation.