Nonsingular multidimensional cosmologies with Lobachevsky spatial sections
Abstract
Description
Examples of nonsingular cosmological models are presented on the basis of exact solutions to multidimensional gravity equations. These examples involve pure imaginary scalar fields, or, in other terms, ``phantom'' fields with an unusual sign of the kinetic term in the Lagrangian. We show that, with such fields, hyperbolic nonsingular models with a cosmological bounce (unlike spherical and spatially flat models) emerge without special relations among the integration constants, i.e., without fine tuning. In such models, the extra-dimension scale factors as well as scalar fields evolve smoothly between different finite asymptotic values. Examples of theories which create phantom scalar fields are obtained from string-inspired multidimensional field models and from theories of gravity in integrable Weyl space-times.
10 pages, submitted to Proc. Int. School GAS04, Kiten, Bulgaria, June 10-16, 2004
10 pages, submitted to Proc. Int. School GAS04, Kiten, Bulgaria, June 10-16, 2004