Single-brane cosmological solutions with a stable compact extra dimension - art. no. 106004

We consider 5-dimensional cosmological solutions of a single brane. The cor rect cosmology on the brane, i.e., governed by the standard 4-dimensional F riedmann equation, and stable compactification of the extra dimension is gu aranteed by the existence of a nonvanishing (T) over cap(5)(5) which is pro portional to the 4-dimensional trace of the energy-momentum tensor. We show that this component of the energy-momentum tensor arises from the back rea ction of the dilaton coupling to the brane. The same positive features are exhibited in solutions found in the presence of nonvanishing cosmological c onstants both on the brane (Lambda(br)) and in the bulk (Lambda(B)). Moreov er, the restoration of the Friedmann equation, with die correct sign, takes place for both signs of Lambda(B), so long as the sign of Lambda(br) is op posite Lambda(B) in order to cancel the energy densities of the two cosmolo gical constants. We further extend our single-brane thin-wall solution to a llow a brane with finite thickness.