Using the loose ends of the SM as lampposts I will present new theories that improve ourunderstanding of Nature at the most fundamental level. In part I, after a brief review of the Standard Model (SM) of particle physics, I enumerate the reasons why we need to go beyond. Part two and three of this thesis contain original research based on several articles that I have completed during the last years. The former focuses on the interplay between the origin of the neutrino mass and the nature of dark matter. On the other hand, part three is devoted to different open problems in physics: the origin flavor and the quantum numbers of elementary particles.... [Leer más...]