Exploring the Frontiers of Standard Model : Neutrinos and Dark Matter, 2021-2025

This thesis studies the SM and its shortcomings and proposes theoretical models that solve some of the phenomenological problems of the SM. The models must render a viable DM candidate and give a Dirac neutrino mass term. In the first chapter, we extend the SM symmetry group with two global symmetries, for this reason, we consider a model that analyzes a scenario where the PQ mechanism solves the strong CP problem and generates a Dirac mass term for neutrinos. Besides, a remnant symmetry guarantees the existence of a WIMP DM candidate in addition to the axion. The WIMP DM phenomenology resembles the well-known singlet-doublet fermion DM. Still, we show that the low mass regime is recovered because of the new annihilation channels that result from the PQ mechanism that allows DM annihilation into neutrinos. This model solves the DM problem and generates neutrino masses and it could be tested in future experiments of DD of DM. Furthermore, we demonstrate that future neutrino telescopes will test the MeV region for DM masses where DD searches are not sensitive. Then, we consider models with an extra Abelian gauge symmetry that solve two phenomenological problems of SM: the lack of a viable DM candidate and the absence of a mechanism that renders a viable Dirac mass term for neutrinos. For this reason, we found around one thousand solutions to the anomaly-free conditions of local Abelian extensions of the SM with N integers that include the ones forming the effective set of Dirac neutrinos and a dark sector with massive fermions. We classify the solutions in 48 types depending on whether the symmetry is dark or active, the dimension of the effective Dirac neutrino mass operator, the number of independent dark matter candidates, and the number of generations of each massive fermion. Finally, we show a model with a two-component DM candidate and a one loop Dirac mass term for neutrinos. In other words, we obtain a complete UV realization of a secluded WIMP dark matter model with an extra Abelian gauge symmetry that includes two-component dark matter candidates, where Dirac neutrino masses are generated at one loop via a scotogenic realization of the effective operator for Dirac neutrino masses in the SM. In summary, this thesis explores the frontiers of SM regarding neutrino masses and dark matter and shows models that can solve two of the phenomenological problems of SM. Those models have a rich phenomenology and can be tested in different searches for new physics.

• Autores: Suárez Roldán, David Alejandro
• Tipo de recurso: Doctoral thesis
• Fecha de publicación: 2025
• Institución: Universidad de Antioquia
• Repositorio: Repositorio UdeA
• Idioma: eng
• OAI Identifier: oai:bibliotecadigital.udea.edu.co:10495/46106
• Acceso en línea: https://hdl.handle.net/10495/46106
• Palabra clave: Dark matter (Astronomy); Materia oscura (Astronomía); Neutrinos - Mass; Neutrinos - Masa; Axions; Axiones; Quantum field theory; Teoría cuántica de campos; Universe; Universo; Majorana fermions - Experiments; Fermiones de Majorana - Experimentos; http://id.loc.gov/authorities/subjects/sh87007317; http://id.loc.gov/authorities/subjects/sh88006832; http://id.loc.gov/authorities/subjects/sh92001911; http://id.loc.gov/authorities/subjects/sh85109461; http://id.loc.gov/authorities/subjects/sh2010007248; http://id.loc.gov/authorities/subjects/sh2020005915
• Rights: openAccess
• License: http://creativecommons.org/licenses/by-nc-sa/4.0/