A stringy origin of the recent acceleration

Inspired by the current observations that the ratio of the abundances of dark energy and matter density is close to one, we provide a string inspired phenomenological model where we try to explain this order one ratio, smallness of the cosmological constant, and also the recent cosmic acceleration. We observe that any effective theory motivated by higher-dimensional physics provides radion/dilaton couplings to the standard model and the dark matter component with different strengths. Provided radion/dilaton is a dynamical field we then show that the dark energy component tracks matter density and can start to dominate very recently.