Closed Inhomogeneous String Cosmologies
Abstract
We present a general algorithm which permits to construct solutions in string cosmology for heterotic and type-IIB superstrings in four dimensions. Using a chain of transformations applied in sequence: conformal, T-duality and SL(2,R) rotations, along with the usual generating techniques associated to Geroch transformations in Einstein frame, we obtain solutions with all relevant low-energy remnants of the string theory. To exemplify our algorithm we present an inhomogeneous string cosmology with S3 topology of spatial sections, discuss some properties of the solution and point out some subtleties involved in the concept of homogeneity and isotropy in string cosmology.
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