http://repositorio.ugto.mx/handle/20.500.12059/4225 Fri, 29 May 2026 18:53:36 GMT 2026-05-29T18:53:36Z http://repositorio.ugto.mx/handle/20.500.12059/13949 Title: Higher-Order dark matter: from non-relativistic Proca stars to cosmological spinor production Authors: Preciado Govea, Edgar Iván Contributor: Diez Tejedor, Alberto Abstract: This thesis explores the possibilities of forming compact dark matter objects as solutions to the Einstein-Klein-Gordon and Einstein-Proca field equations, as well as accounting for the mechanism of dark matter production through gravitational particle production. According to quantum mechanics, particles are subdivided into two groups: those with integer spin (bosons) and those with half-integer spin (fermions). The former are capable of forming particle condensates in the ground state, while the latter, limited by FermiDirac statistics, are forced to successively occupy higher energy levels. Here we will focus on describing the equilibrium configurations of compact objects of self-gravitating and self-interacting particles with spin s = 0 and s = 1, which share similar characteristics to their counterparts, the compact objects composed of fermions. On the other hand, one of the most notable results of the semiclassical treatment of quantum fields on curved spaces predicts the gravitational production of particles due to gravitational effects, in abundances that could account for the dark matter bounds imposed by current observations [4, 5]. Here we will focus on describing this phenomenon for quantum fields with spin s = 0 and spin s = ½ at different orders of approximation. In both objectives, we describe dark matter as a field that interacts only gravitationally with the rest of the matter. Both objectives aim to address particular issues (one intends to solve astrophysical and cosmological problems, while the other intends to explain the mechanism of production of these particles); however, they equally intend to account for the gravitational presence of dark matter in the observable universe. In both cases, we will explore different regimes of approximations for the bosonic or fermionic dark matter field according to each chapter. Wed, 01 Jan 2025 00:00:00 GMT http://repositorio.ugto.mx/handle/20.500.12059/13949 2025-01-01T00:00:00Z http://repositorio.ugto.mx/handle/20.500.12059/13886 Title: Electrical and magnetic stimulation for the treatment of patients with cardiac and neurological conditions Authors: Rodríguez Calvo, Edwin Fernando Contributor: Córdova Fraga, Teodoro Abstract: Electrical stimulation and electrophysiological signal analysis have proven to be key tools in biomedical research and the development of therapeutic devices. Various studies have explored their application in the modulation of nervous system activity, the treatment of pathologies such as migraines and arrhythmias, and the identification of neuronal biomarkers through EEG. In this context, non-invasive electrical stimulation devices have been developed with the ability to vary key parameters such as frequency, current, and pulse width, allowing personalized adaptation for the research and treatment of conditions related to the vagus nerve. A system has been designed to correct arrhythmias by means of bioelectromagnetic stimulation of the sinus node and cervical sympathetic ganglia, demonstrating a promising response in heart rhythm regulation. Likewise, studies have been conducted on the relationship between brain activity and migraines through the analysis of EEG signals. Interactive games have been designed to induce states of concentration and activate specific brain regions, providing a possible electrophysiological biomarker of migraines. In addition, a neuromodulation device has been developed for the simultaneous stimulation of the vagus and trigeminal nerves, evaluating its effect on pain reduction and cognitive activity by recording EEG signals from the prefrontal lobe. These advances reflect the potential of biomedical technology in the exploration of the nervous system and the development of alternative therapies for various pathologies, offering new perspectives in the research and treatment of neurological and cardiovascular diseases. Tue, 01 Jul 2025 00:00:00 GMT http://repositorio.ugto.mx/handle/20.500.12059/13886 2025-07-01T00:00:00Z http://repositorio.ugto.mx/handle/20.500.12059/13715 Title: Study of heavy baryons phenomenology Authors: Ailier Rivero Acosta Contributor: Elena Santopinto Abstract: El objetivo de esta investigación es estudiar las propiedades de los bariones con un solo quark pesado dentro del marco del modelo de quarks constituyentes. Este estudio se centra en el cálculo de los espectros de masa y de las anchuras de decaimiento fuerte y electromagnético para los bariones con un quark bottom, así como en las anchuras de decaimiento electromagnético para los bariones con un quark charm. Los espectros de masa se calculan utilizando un modelo de quarks, mientras que para analizar los canales de sabor abierto en la desintegración fuerte de los bariones con un quark bottom se emplea el modelo 3P0. Las anchuras de decaimiento electromagnético para los bariones con un quark bottom se calculan desde los estados bases hasta los estados de la segunda banda de energía utilizando el Hamiltoniano de las interacciones electromagnéticas en la aproximación no relativista. Para los bariones con un quark charm, las anchuras de decaimiento electromagnético se determinan específicamente para los estados P-wave del Ξc . Se introduce un método novedoso para el cálculo de las anchuras de decaimiento electromagnético. Este innovador enfoque permite la evaluación completamente analítica de las amplitudes de transición sin necesidad de introducir aproximaciones adicionales como las utilizadas en artículos previos en el sector de los bariones pesados. En particular, este trabajo representa el primer estudio teórico de los decaimientos electromagnéticos de los estados Dρ-wave, los estados mixtos ρλ y los estados excitados radialmente en ρ y λ. Wed, 07 May 2025 00:00:00 GMT http://repositorio.ugto.mx/handle/20.500.12059/13715 2025-05-07T00:00:00Z http://repositorio.ugto.mx/handle/20.500.12059/13595 Title: Cosmological solutions for a two branes system in a generalized Randall-Sundrum model Authors: JUAN LUIS PEREZ PEREZ Contributor: Luis Arturo Ureña López Abstract: En la presente tesis se discute el problema de la inflación cosmológica en etapas tempranas del universo en el contexto del modelo 5 dimensional de Randall y Sundrum. Mediante la solución de las ecuaciones de Einstein para una métrica general en un sistema de dos branas, se obtienen ecuaciones cosmológicas que relacionan la evolución en el tiempo de los componentes de energía en cada brana. Estas restricciones son debidas a la forma de la geometría del espacio-tiempo. Sat, 01 Feb 2025 00:00:00 GMT http://repositorio.ugto.mx/handle/20.500.12059/13595 2025-02-01T00:00:00Z