2002/07/23 by K. A. Bronnikov, Kirill A Bronnikov, J. C. Fabris +1
Physics and Astronomy · #Black Holes and Theoretical Physics #Cosmology and Gravitation Theories #Dilaton #Effective action #Fine-tuning #Moduli #Noncommutative and Quantum Gravity Theories #Scale factor (cosmology) #Singularity #String (physics) #String cosmology #Supergravity #Superstring theory #gr-qc #hep-th
paper · pdf · doi:10.1088/1126-6708/2002/09/062
published as JHEP 0209:062,2002 · Latex 2e, 9 pages
arxiv created 2002/07/23 · openalex publication_date 2002/09/30 · arxiv updated 2014/11/17 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
Exact cosmological solutions for effective actions in D dimensions inspired by the tree-level superstring action are studied. For a certain range of free parameters existing in the model, nonsingular bouncing solutions are found. Among them, of particular interest can be open hyperbolic models, in which, without any fine tuning, the internal scale factor and the dilaton field (connected with string coupling in string theories) tend to constant values at late times. A cosmological singularity is avoided due to nonminimal dilaton-gravity coupling and, for D > 11, due to pure imaginary nature of the dilaton, which conforms to currently discussed unification models. The existence of such and similar solutions supports the opinion that the Universe had never undergone a stage driven by full-scale quantum gravity.