Talk detail

Participant	Kanti, Panagiota
Institution	University of Ioannina - Panepistimioupolis - Ioannina - Epirus - Greece

Session	EU3	Accepted		Order	Time
Talk	Oral abstract	Title	Early-Time Cosmological Solutions in Scalar-Gauss-Bonnet Theories
Coauthors
Abstract	We consider a gravitational theory that contains the Einstein term, a scalar field and the quadratic Gauss-Bonnet term. We focus on the early-universe dynamics, and demonstrate that a simple choice of the coupling function between the scalar field and the Gauss-Bonnet term and a simplifying assumption regarding the role of the Ricci scalar can lead to new, analytical, elegant solutions with interesting characteristics. We first demonstrate, in the context of two different models, that the Ricci scalar does not affect the actual cosmological solutions at early times, when the curvature is strong. We therefore consider a pure scalar-GB theory with a quadratic coupling function: for a negative coupling parameter, we obtain inflationary, de Sitter-type solutions or expanding solutions with a de Sitter phase in their past and a natural exit mechanism at later times; for a positive coupling function, we find instead singularity-free solutions with no Big-Bang singularity.
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