Tensor-multiscalar theories from multidimensional cosmology.

Inhomogeneous multidimensional cosmological models with a higher dimensional spacetime manifold M = M0 × ∏n i=1 Mi (n ≥ 1) are investigated under dimensional reduction to tensor-multi-scalar theories. In the Einstein conformal frame, these theories take the shape of a flat σ-model. For the singular case where M0 is 2-dimensional, the dimensional reduction to dilaton gravity is preformed with different distinguished representations of the action. PACS number(s): 04.50.+h, 98.80.Hw, 04.60.Kz This work was financially supported by DFG grants 436 RUS 113/7/0, 436 UKR 17/7/95, and the DAAD. 1