History of cosmic evolution with modified Gauss-Bonnet-dilatonic coupled term

Understand

Gauss-Bonnet-dilatonic coupling in four dimension plays an important role to explain late time cosmic evolution.

• However, this term is an outcome of low energy string effective action and thus ought to be important in the early universe too.
• Unfortunately, phase-space formulation of such a theory does not exist in the literature due to branching.
• We therefore consider a modified theory of gravity, which contains a nonminimally coupled scalar-tensor sector in addition to higher order scalar curvature invariant term with Gauss-Bonnet-dilatonic coupling.