Braneworld effective action and origin of inflation

We construct a braneworld effective action in the two-brane Randall-Sundrum model and show that the radion mode plays the role of a scalar field localizing the nonlocal part of this action. The nonminimal curvature coupling of this field reflects the violation of AdS-CFT correspondence for finite values of brane separation. Under a small detuning of the brane tension from the Randall-Sundrum flat brane value, the radion mode can play the role of the inflaton. Inflationary dynamics corresponds to branes moving apart in the field of the repelling interbrane inflaton-radion potential and implies the existence of an acceleration stage caused by a remnant cosmological constant at late (large brane separation) stages of evolution. We discuss the possibility of fixing the initial conditions in this model within the concept of braneworld creation from the tunneling or no-boundary cosmological state, which formally replaces the conventional moduli stabilization mechanism.