2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/33648This paper summarizes the contribution presented at the {\sl IX Marcel Grossmann Meeting} (Rome, July 2000). It is stressed, in particular, that a non-relativistic background of ultra-light dilatons, produced in the context of string cosmology, could represent today a significant fraction of cold dark matter. If the dilaton mass lies within the resonant band of present gravitational antennas, a stochastic dilaton background with a nearly critical density could be visible, in principle, already at the level of sensitivity of the detectors in operation and presently under construction.2 pages, Latex, summary of the contribution presented at the IX Marcel Grossmann Meeting (Rome, July 2000). To appear in the proceedings (World Scientific, Singapore)General Relativity and Quantum Cosmologytext