Heterotic Mtheory cosmology in four and five dimensions
Abstract
We study rolling radii solutions in the context of the four and fivedimensional effective actions of heterotic M theory. For the standard fourdimensional solutions with varying dilaton and T modulus, we find approximate fivedimensional counterparts. These are new, generically nonseparating solutions corresponding to a pair of fivedimensional domain walls evolving in time. Loop corrections in the fourdimensional theory are described by certain excitations of fields in the fifth dimension. We point out that the two exact separable solutions previously discovered are precisely the special cases for which the loop corrections are time independent. Generically, loop corrections vary with time. Moreover, for a subset of solutions they increase in time, evolving into complicated, nonseparating solutions. In this paper we compute these solutions to leading, nontrivial order. Using the equations for the induced brane metric, we present a general argument showing that the accelerating backgrounds of this type cannot evolve smoothly into decelerating backgrounds.
 Publication:

Physical Review D
 Pub Date:
 December 2000
 DOI:
 10.1103/PhysRevD.63.026003
 arXiv:
 arXiv:hepth/0003256
 Bibcode:
 2000PhRvD..63b6003B
 Keywords:

 11.25.Mj;
 04.50.+h;
 11.27.+d;
 Compactification and fourdimensional models;
 Gravity in more than four dimensions KaluzaKlein theory unified field theories;
 alternative theories of gravity;
 Extended classical solutions;
 cosmic strings domain walls texture;
 High Energy Physics  Theory
 EPrint:
 15 pages, Latex, 1 eps figure