Two Micron‐Size Dark Dimensions
Luis A. Anchordoqui, Ignatios Antoniadis, Dieter Lüst
Abstract
Abstract Two extra dimensions of micron scale might simultaneously address the gauge and cosmological hierarchy problems. In this paper various observational bounds in scenarios with one and two large extra dimensions are examined, to see if they are compatible with the micron scale. The authors show that consistency with astrophysical observations requires that two extra dimensions of micron scale must not admit isometries, whereby conservation of the extra dimensional momentum is violated, allowing the massive Kaluza–Klein modes of the graviton to decay to other lighter graviton modes. However, to remain consistent with cosmological observations two extra dimensions of micron scale require a delicately fine tuning of the temperature at which the universe enters the radiation dominated epoch. Diving into this fine‐tuned scenario the authors also show that primordial black holes with masses in the range could make all cosmological dark matter.