2008/03/03 by Natalia Shuhmaher, Shuhmaher, Natalia
Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Phenomenology (hep-ph) #High Energy Physics - Theory (hep-th) #hep-ph #hep-th
paper · pdf · doi:10.48550/arxiv.0803.0216
8 pages, 2 figures, content changed, references added
arxiv created 2009/01/07 · arxiv updated 2009/12/01
We discuss the entropy and the size/homogeneity/horizon problems in power-law expanding universes with one scale initial conditions. We set the minimal scale Λ= 1025 GeV at which a non-inflationary solution is possible and show that the radiation dominated epoch alone technically is not able to explain the issue. An earlier paper on the subject, [1], attempts a multidimensional scenario. We review the scenario of the paper [1] in an effective four dimensional Einstein frame. We find that during contraction of extra dimensions, the residual bulk energy density is important and leads to a scaling solution. The existence of this scaling solution is a new result. We provide a numerical example which demonstrates the evolution of the scale factor and the extra dimensions. In the whole, the validity of the effective field theory calculations at the scale of Λ= 1025 GeV is under question and, hence, the final conclusion regarding the possibility of a non-inflationary solution is preliminary.