2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/41550The scale--independence of the primordial curvature perturbation suggests that it comes from the vacuum fluctuation during inflation of a light scalar field. This field may be the inflaton, or a different `curvaton' field. The observation of primordial non--gaussianity would be a smoking gun for the curvaton model, while the observation of gravitational waves originating during slow--roll inflation would rule out the model.Invited talk at Moriond `The Cosmological Model'. v2 corrects minor typos and alters a few wordsHigh Energy Physics - PhenomenologyAstrophysicsHigh Energy Physics - Theorytext