ABSTRACT
We consider a model in which the Universe is the direct product of an ordinary (3+1)-dimensional space--a brane where all the standard model fields are confined-and a compact hyperbolic manifold. The decay of massive Kaluza-Klein modes leads to the injection of bulk entropy into the observable Universe. The large statistical averaging inherent in the collapse of the initial entropy onto the brane smoothes out any initial inhomogeneities in the distribution of matter and of three-curvature.
ABSTRACT
We reconsider theories with low gravitational (or string) scale M(*) where Newton's constant is generated via new large-volume spatial dimensions, while standard model states are localized to a 3-brane. Utilizing compact hyperbolic manifolds we show that the spectrum of Kaluza-Klein modes is radically altered. This allows the early Universe to evolve normally up to substantial temperatures, and completely negates the astrophysical constraints on M(*). Furthermore, an exponential hierarchy between the usual Planck scale and the true fundamental scale of physics can emerge with only O(1) coefficients. The linear size of the internal space remains small. The proposal has striking testable signatures.
