  Given a bulk scalar field with sufficient self-interactions in a higher
dimensional spacetime, it is shown that the continuous symmetries in four
dimensions, induced by the topological structure of the compact manifold,
naturally lead to formation of stable nontopological solitons of Q-ball type.
The mass per unit charge inside the soliton is bounded by the size of the extra
dimensions, and it is thus stable with respect to decaying into excited levels
of all bulk fields, irrespective of their bulk masses. A familiar example is
the Standard Model in the bulk, where the Kaluza-Klein levels of the Higgs
boson form a stable Q-ball. These stable solitons are natural candidates for
the dark matter in the Universe.
