The Need of Dark Energy for Dynamical Compactification of Extra   Dimensions on the Brane
  We consider a six-dimensional braneworld model and we study the cosmological evolution of a (4+1) brane-universe. Introducing matter on the brane we show that the scale factor of the physical three-dimensional brane-universe is related to the scale factor of the fourth dimension on the brane, and the suppression of the extra dimension compared to the three dimensions requires the presence of dark energy. 
Bertha Cuadros-Melgar and Eleftherios Papantonopoulos