2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/213207A set of cosmological models that takes into account the variation of the particle number is presented. In this context both dark matter and dark energy can be explained using a single component, without assuming any exotic equation of state, solving directly the cosmic coincidence problem.5 pages, 2 figuresAstrophysicstext