Dynamically generated inflationary two-field potential via non-Riemannian volume forms

Understand

We consider a simple model of modified gravity interacting with a single scalar field $\varphi$ with weakly coupled exponential potential within the framework of non-Riemannian spacetime volume-form formalism.

• The specific form of the action is fixed by the requirement of invariance under global Weyl-scale symmetry.
• Upon passing to the physical Einstein frame we show how the non-Riemannian volume elements create a second canonical scalar field $u$ and dynamically generate a non-trivial two-scalar-field potential $U_{\rm eff}(u,\varphi)$ with two remarkable features: (i) it possesses a large flat region for large $u$ describing a slow-roll inflation; (ii) it has a stable low-lying minimum w.r.t.
• $(u,\varphi)$ representing the dark energy density in the "late universe".