Detecting neutrinos, especially ultra-high-energy (UHE) neutrinos, is inherently challenging. Highly sensitive detection devices are required to effectively capture these rare particles, which often results in significant noise in the data. This project focuses on enhancing the detection sensitivity of UHE neutrinos interacting with glacier ice by employing deep learning and transformer models. These models are trained on simulated data that mimics the radio signals produced by neutrino interactions in ice. The developed models have demonstrated improved performance compared to current hardware implementations, offering a promising advancement in neutrino detection technology.

Revisamos sistemáticamente el proceso de producción de di-muones vía la dispersión de neutrinos en el campo Coulombiano del núcleo, conocido como producción tridente de neutrinos. A pesar de que este proceso tiene una sección de choque pequeña comparada con el proceso de dispersión neutrino-núcleo vía corriente cargada inclusiva en el Modelo Estándar, se caracteriza por una señal experimental muy clara. El par de muones cargados opuestamente es caracterizado investigando sus distribuciones cinemáticas. Para esto, hemos implementado una simulación detallada del proceso de producción tridente de neutrinos en el generador de eventos Montecarlo GENIE; y analizamos y simulamos los backgrounds relevantes. También exploramos métodos de Análisis Multivariado para mejorar la selección de la señal en el contexto de detectores tipo MINERVA y DUNE como representantes de experimentos de neutrinos de aceleradores presentes y venideros. / We systematically review the di-muon production via neutrino scattering off the Coloumb éld of nuclei, referred to as neutrino trident production. While this process has a small cross section compared to the SM charged-current inclusive neutrino nucleus channel, it features a very clear experimental signature. The oppositely charged muons are characterized by investigating their kinematical distributions. For this, we have implemented a very detailed simulation of neutrino trident production in the GENIE MC and make an analysis and simulation of relevant backgrounds. We further explore Multivariate Analysis methods to enhance signal selection in the context of a MINERVA-like and DUNE-like detectors as representative of current and forthcoming accelerator-based neutrino experiments.

El fenómeno de oscilaciones de neutrinos ha sido extensamente estudiado experimentalmente y teóricamente en las últimas décadas. Esto no sólo implicó su confirmación sino también la medida de casi todos los parámetros asociados a ésta. Sin embargo, aún quedan pendientes algunas incógnitas por resolver como son la jerarquía de las masas de los neutrinos, la determinación de la fase que viola la simetría carga-paridad, el problema de las degeneraciones, entre otras. Para poder ser resueltos muchos de estos problemas requieren experimentos de gran escala y con la más óptima tecnología para la detección de neutrinos. El experimento DUNE (Deep Underground Neutrino Experiment) tendrá estas capacidades. Este experimento tiene una distancia fuente – detector de 1300km contando con un detector cercano de alta precisión y uno lejano de 40 kton hecho de Argón Líquido. Estas características no sólo permitirán resolver los problemas mencionados sino que además permitirán estudiar, por ejemplo, neutrinos provenientes del colapso de supernovas, así como el decaimiento del protón, entre otros procesos. En esta tesis se ha realizado una revisión detallada de la física de oscilación de neutrinos tanto en vacío como en materia, incorporando a este último el decaimiento invisible de neutrinos. Este fenómeno aunque descartado hoy para la explicación del problema de los neutrinos solares y atmosféricos. Tiene Actualmente una relevancia como un efecto subdominante dentro de las oscilaciones de neutrinos. Haciendo que la probabilidad de oscilación sufra un amortiguamiento. En esta tesis estudiaremos la sensibilidad de DUNE al nuevo parámetro que corresponde al decaimiento invisible de neutrinos. Viendo como distintos valores de este parámetro modifican el espectro de energía producido por los eventos que se observarían en DUNE. Nuestras simulaciones han sido hechas utilizando el paquete GLoBES (General Long Baseline Experiment Simulator) y usando como datos de entrada inputs, distribuciones proporcionadas por el propio experimento.

The discovery of the Higgs boson in the 8 TeV run of the LHC [1, 2] marks one of the most important milestones in particle physics. Its mass is already known rather precisely: mh = 125.09 ± 0.21 (stat.) ±0.11 (syst.) GeV [3], and the signal strength of various LHC searches has been found consistent with the SM predictions. While this completes the Standard Model (SM) particle-wise, several questions still remain open, for example: (i) Is it possible to include the SM in a grand unified theory where all gauge forces unify? (ii) Is there a particle physics explanation of the observed dark matter relic density? (iii) What causes the hierarchy in the fermion mass spectrum and why are neutrinos so much lighter than the other fermions? What causes the observed mixing patterns in the fermion sector? (iv) What stabilizes the Higgs mass at the electroweak scale? Supersymmetric model address several of these questions and consequently the search for supersymmetry (SUSY) is among the main priorities of the LHC collaborations. Up to now no significant sign for physics beyond SM has been found. The combination of the Higgs discovery with the (yet) unsuccessful searches has led to the introduction of a model class called ‘natural SUSY’ [4–15]. Here, the basic idea is to give electroweak-scale masses only to those SUSY particles giving a sizeable contribution to the mass of the Higgs boson, such that a too large tuning of parameters is avoided. All other particle masses are taken at the multi-TeV scale. In particular, masses of the order of a few hundred GeV up to about one TeV are assigned to the higgsinos (the partners of the Higgs bosons), the lightest stop (the partner of the top-quark) and, if the latter is mainly a left-stop, also to the light sbottom In addition the gluino and the heavier stop masses should also be close to at most a few TeV. Neutrino oscillation experiments confirm that at least two neutrinos have a non-zero mass. The exact mass generation mechanism for these particles is unknown, and both the SM and the MSSM remain agnostic on this topic. Although many ways to generate neutrino mass exist, perhaps the most popular one is the seesaw mechanism [16–21]. The main problem with the usual seesaw mechanisms lies on the difficulty in testing its validity. In general, if Yukawa couplings are sizeable, the seesaw relations require Majorana neutrino masses to be very large, such that the new heavy states cannot be produced at colliders. In contrast, if one requires the masses to be light, then the Yukawas need to be small, making production cross-sections and decay rates to vanish. A possible way out of this dilemma lies on what 3 is called the inverse seesaw [22], which is based on having specific structures on the mass matrix (generally motivated by symmetry arguments) to generate small neutrino masses. This, at the same time, allows Yukawa couplings to be large, and sterile masses to be light. We consider here a supersymmetric model where neutrino data are explained via a minimal inverse seesaw scenario where the gauge-singlet neutrinos have masses in the range O(keV) to O(100 GeV). We explore this with a parametrization built for the standard seesaw, and go to the limit where the inverse seesaw emerges, such that Yukawas and mixings become sizeable. Although non-SUSY versions of this scenario can solve the dark matter and matter-antimatter asymmetry problems [23–25], we shall make no claim on these issues in our model. In view of the naturalness arguments, we further assume that the higgsinos have masses of O(100 GeV), whereas the gaugino masses lie at the multi-TeV scale (see [26] for an example of such a scenario). In addition, we assume all squarks are heavy enough such that LHC bounds are avoided, and play no role in the phenomenology within this work1. In contrast we allow for fairly light sleptons and investigate the extent to which current LHC data can constrain such scenarios. This paper is organized as follows: in the next section we present the model. Section III summarizes the numerical tools used and gives an overview of the LHC analysis used for these investigations. In Section IV we present our findings for the two generic scenarios which differ in the nature of the lighest supersymmetric particle (LSP): a Higgsino LSP and a sneutrino LSP. In Section V we draw our conclusions. Appendices A and B give the complete formulae for the neutrino and sneutrino masses.

We apply the Jansson-Farrar JF12 magnetic field model in the context of point source searches by correlating the Telescope Array ultrahigh energy cosmic ray data and the IceCube-40 neutrino candidates, as well as other magnetic field hypotheses. Our field hypotheses are: no magnetic field, the JF12 field considering only the regular component, the JF12 full magnetic field, which is a combination of regular and random field components, and the standard turbulent magnetic field used in previous correlation analyses. As expected from a neutrino sample such as IceCube-40, consistent with atmospheric neutrinos, we have found no significant correlation signal in all the cases. Therefore, this paper is mainly devoted to the comparison of the effect of the different magnetic field hypotheses on the minimum neutrino source flux strength required for a 5σ discovery and the derived 90% C.L. upper limits. We also incorporate in our comparison the cases of different power law indices α= 2.2, α=2.5 for the neutrino point source flux. The differences in the 5σ discovery flux for our magnetic field hypotheses is ∼1%–50%, being the maximum difference with the regular JF12 field and standard turbulent field models, being the standard turbulent higher than the regular one, while the minimum is between the no magnetic field and regular JF12 field. Considering the current flux upper limits, we find that IceCube requires a lifetime ≳5 years to observe neutrino-UHECR correlation signals. Our analysis for different power law indices yielded the same relative behavior between different magnetic field models.

This thesis tackles two essential topics of neutrino physics: neutrino decay and neutrino cross-section measurement. First, the invisible and visible neutrino decay is analyzed through a phenomenological approach, considering future long-baseline neutrino experiments such as DUNE and a hypothetical neutrino beam toward the ANDES laboratory. The study takes into account the νμ and νe disappearance and appearance, respectively, for both FHC and RHC flux modes. The results showed a negligible matter effect for DUNE but significantly more notable at ANDES. At 90% C.L., the sensitivity to the decay parameter α3 can be as small as 2 × 10−6 eV2 for a chosen coupling. The impact of neutrino decay in the determination of θ23 and δCP were also shown. Second, the double-differential cross-section measurement for νμ-carbon interactions with three-momentum transfer |q| < 1.2 GeV obtained with medium energy exposures in the NuMI beam at MINERvA experiment are reported. The measurement is presented as a function of |q| and Eavail and reviews different interaction models and nuclear effects along quasi-elastic to resonance processes to define a new model for a better agreement. The double differential cross sections are compared to the MnvTunes, GENIE, and NuWro predictions. / Esta tesis aborda dos temas esenciales de la física de neutrinos: el decaimiento de neutrinos y la sección transversal de neutrinos. En primer lugar, el decaimiento invisible y visible de neutrinos se analiza a través de un enfoque fenomenológico, considerando dos futuros experimentos de neutrinos de long baseline como DUNE y asumiendo un hipotético haz de neutrinos hacia el laboratorio ANDES. El estudio concidera la desaparición y aparición de νμ y νe, respectivamente, para los modos de flujo neutrinos FHC y RHC. Los resultados mostraron un efecto de materia insignificante para DUNE, en contraste, más notable en ANDES. A 90% C.L., la sensibilidad al parámetro de decaimiento α3 puede ser tan pequeña como 2 ×106 eV2 para un acoplamiento dado. Tambise mostra el impacto de la desintegración de neutrinos en la determinación de θ23 y δCP . En segundo lugar, la medición de la sección transversal diferencial doble para las interacciones νμ-carbono con transferencia de momentum |q| < 1.2 GeV obtenidos con una exposición a la energía media de neutrinos en el haz NuMI en el experimento MINERvA. La medida se presenta en función de |q| y Eavaill, además se revisa diferentes modelos de interacción y efectos nucleares a lo largo de procesos cuasi-elásticos a resonantes para definir un nuevo modelo para un mejor acuerdo con los datos. Las secciones transversales diferenciales dobles se comparan con las predicciones de MnvTunes, GENIE y NuWro.

We studied dimuon events arising from trident production, for both coherent and incoherent processes, as well as relevant backgrounds, in order to predict the number of expected events observed in the lifetimes of current and forthcoming neutrino experiments. In particular, for this thesis, we focused in building the implementation of the incoherent contribution within the context of the GENIE montecarlo generator. We also developed relatively detailed GEANT4 geometries for the MINERvA detector as well as the DUNE Near Detector, for the Liquid Argon (LArTPC) and Straw Tube Tracker (STT) proposals. A very careful study of the backgrounds for the incoherent case was carried, in order to complement the study already done for the coherent contribution. Then, we combined the signals for the coherent and incoherent processes to realize a more realistic study of the expected number of events. The ROOT TMVA package for multivariate analysis was then used to filter signal from background. The results are presented in terms of number of events, and are calibrated based on the detector exposure in the lifetime of the MINERvA detector and DUNE Near Detector.

The Standard Model (SM) of particle physics consists in a description of all the known elemen-tary particles and their interactions. As far as it is known, the SM has passed all experimental tests, but presents some imperfections such as the presence of neutrino masses and the hierarchy problem. This encourages to probe theories beyond the Standard Model (BSM) that could bring solutions to these problems. An interesting proposal is to search for neutral long lived particles (LLP). These type of particles have long decay lengths and can be generated by a variety of BSM models such as Supersymmetry (SUSY), which proposes a solution to the hierarchy problem, and the Seesaw Mechanism that generates massive neutrinos. The detection of the decay products of LLPs would contribute to the discovery of new physics. The objective of this work is to develop a toy detector based on C++ and Pythia8 with the purpose of creating a tool for searches of neutral long lived particles. All the features, including the geometric characteristics and the particle accep- tance are constructed with information from the sub detectors of the CMS experiment. We use a Minimal SUSY process that violates R parity (RPVMSSM) to simulate processes producing LLPs in MadGraph5 and study the response of the toy detector. We conclude our simulation properly recreates important experimental conditions, and is suitable as a first step towards an international competitive particle physics tool.

En el modelo estandar de física de partículas, los neutrinos son descritos en terminos de fermiones no masivos con quiralidad de mano izquierda. Sin embargo, la observación de las oscilaciones de neutrinos implica que los neutrinos tienen masa. Esto incentiva la búsqueda de extensiones del modelo estándar que expliquen la masa de los neutrinos. Uno de estos modelos es el dimension-5 seesaw portal, en el cual se utiliza una combinación del mecanismo seesaw tipo 1 y operadores efectivos de dimensión cinco para modificar el lagrangiano del modelo estándar. El objetivo de este trabajo es derivar fórmulas para calcular la anchura de decaimiento de neutrinos pesados, en un modelo dimensión-5 seesaw portal que añade tres neutrinos masivos de Majorana con quiralidad de mano derecha, con masas en el rango GeV. Los resultados obtenidos fueron graficados para analizar la importancia de cada termino y se encontró que la contribución proveniente de los términos de decamientos a tres cuerpos con operadores de dimensión cinco es pequeña. Esto es debido a que su inclusión reduce la distancia que podría viajar el neutrino antes de desintegrarse en un pequeño porcentaje < 6%. Por lo que si bien son necesarios para un calculo completo, se pueden excluir estos términos si es que no se requiere alta precisión. / In the Standard Model(SM), neutrinos are described in terms of massless left handed fermions, however the observation of neutrino flavor oscillations indicates non vanishing neutrino masses. This is an incentive for new physics beyond the standard model. One approach to explain neutrino masses is known as dimension-5 seesaw portal, in which the SM Lagrangian is modified using a combination of type I Seesaw and dimension five effective operators. The objective of this work is to derive formulae to compute the three-body decay of heavy neutrinos in a dimension-5 seesaw portal that adds three right handed Majorana neutrinos with masses in the GeV range to the SM. After obtaining the various formulae we plotted the results to analyze the relevance of each term, and found that the removal of the contribution of all terms coming from the three-body decays with dimension five operators only reduce the decay length by a few percent < 6% of the total decay length. Although the inclusion of these terms is necessary for an accurate result, it is possible to exclude them form calculations if precision is not of the utmost importance.

In this thesis I test the modified Newtonian dynamics as an alternative to the cold dark matter hypothesis. In the Milky Way, I show that the dynamics of the dwarf galaxies are well described by the paradigm and I confirm its distant low surface brightness globular clusters provide a strong test, for which I make predictions. Through analysis of a sample of 26 X-ray bright galaxy groups and clusters I demonstrate that the three active neutrinos and their anti-particles are insufficient to reconcile modified Newtonian dynamics with the observed temperatures of the X-ray emitting gas, nor with weak-lensing measurements, in particular for the bullet cluster. To this end, I propose an 11eV sterile neutrino to serendipitously resolve the residual mass problem in X-ray bright groups and clusters, as well as matching the angular power spectrum of the Cosmic Microwave Background. With this in mind, I show that the large collision velocity of the bullet cluster and the high number of colliding clusters is more naturally reproduced in MOND than in standard dynamics.