Gravitational mass in asymptotically de Sitter space-times with compactified dimensions - art. no. 064019

We define the gravitational mass in asymptotically de Sitter space-times wi th compactified dimensions. It is shown that the mass can be negative for a space-time with matter spreading beyond the cosmological horizon scale or having a large outward "momentum" in four dimensions. We give simple exampl es with negative energy in higher dimensions even if the matter is not beyo nd the horizon or the system does not have a large "momentum." They do not have the lower bound on the mass. We also give a positive energy argument i n higher dimensions and realize that the elementary fermion cannot exist in our examples. [S0556-2821(99)03216-6].