2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/55895We review the developments in the past twenty years (which are based on our deformation philosophy of physical theories) dealing with elementary particles composed of singletons in anti De Sitter space-time. The study starts with the kinematical aspects (especially for massless particles) and extends to the beginning of a field theory of composite elementary particles and its relations with conformal field theory (including very recent developments).10 pages, LaTeX2e. To be published in a special issue of Proceedings of Steklov Mathematical Institute dedicated to L.D.FaddeevHigh Energy Physics - TheoryMathematical Physicstext