On cosmologically induced hierarchies in string theory

Abstract

We propose, within a perturbative string theory example, a cosmologicalway to generate a large hierarchy between the observed Planck mass and thefundamental string scale. Time evolution results in three large spacedimensions, one additional dimension transverse to our world and five small internal dimensions with a very slow time evolution. The evolutionof the string coupling and internal space generate a large Planckmass. However, due to an exact compensation between the timeevolution of the internal space and that of the string coupling, thegauge and Yukawa couplings on our universe are time independent.