On the Cosmology and Symmetry of Dilaton-Axion Gravity

Abstract

A global O$(2,2)$ symmetry is found in the Brans-Dicke theory of gravity when the dilaton is coupled to axion and moduli fields. The symmetry is broken if a cosmological constant is introduced. Within the class of spatially homogeneous Bianchi cosmologies, only the type I and V models respect the symmetry. Isotropic cosmological solutions are found for arbitrary spatial curvature. In the region of parameter space relevant to the pre-big bang scenario, the interplay between the scalar fields results in a bouncing cosmology.

11 pages, latex, 2 figures available on request

References in corpus (2)

• Noether symmetries in Bianchi universes
• Inflationary and Deflationary Branches in Extended Pre--Big Bang Cosmology

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