CMB from a Gauss-Bonnet-induced de Sitter fixed point

Understand

In the gravitational effective theories including higher curvature terms, cosmological solutions can have nontrivial de Sitter fixed points.

• We study phenomenological implications of such points, focusing on a theory in which a massive scalar field is nonminimally coupled to the Euler density.
• We first analyze the phase portrait of the dynamical system and show that the fixed point can be a sink or a saddle, depending on the strength of the coupling.
• Then, we compute the perturbation spectra generated in the vicinity of the fixed point in order to investigate whether the fixed point may be considered as cosmic inflation.