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Cosmological Constraints on Theories with Large Extra Dimensions

Lawrence J. Hall, David Smith

hep-pharXiv:hep-ph/9904267

Abstract

In theories with large extra dimensions, constraints from cosmology lead to non-trivial lower bounds on the fundamental scale MF, corresponding to upper bounds on the radii of the compact extra dimensions. These constraints are especially relevant to the case of two extra dimensions, since only if MF is 10 TeV or less do deviations from the standard gravitational force law become evident at distances accessible to planned sub-mm gravity experiments. By examining the graviton decay contribution to the cosmic diffuse gamma radiation, we derive, for the case of two extra dimensions, a conservative bound MF > 110 TeV, corresponding to r2 < 5.1 times 10-5 mm, well beyond the reach of these experiments. We also consider the constraint coming from graviton overclosure of the universe and derive an independent bound MF > 6.5 h(-1/2) TeV, or r2 < .015 h mm.

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