Búsquedas fenomenológicas de nueva física en los sectores del quark top y un bosón Z en el LHC
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Comisión Nacional de Energía Atómica. Gerencia Área Académica. Gerencia Instituto Sabato
Universidad Nacional San Martin. Instituto de tecnología Sabato
Universidad Nacional San Martin. Instituto de tecnología Sabato
Resumen
A través de los últimos años, los avances logrados en el campo experimental de la Física de partículas, asociados a los logros en el Gran Colisionador de Hadrones (o LHC, su sigla en inglés por Large Hadron Collider), han permitido testear como nunca antes al Modelo Estándar (ME). Las predicciones de este modelo se han medido y validado con una precisión sin precedentes, y, sin embargo, la cantidad de fenómenos no explicados y los interrogantes acerca de su estructura no dejan de exhibirla como una teoría efectiva hasta las energías exploradas. La búsqueda de Nueva Física (NF) es uno de los programas claves en el LHC, pero ante resultados que no dan pistas sobre el camino a seguir, las propuestas fenomenológicas cobran mayor relevancia. Estas propuestas pueden resultar fundamentales en los años venideros, no solo para trazar nuevos caminos de búsqueda y para poner límites a teorías más allá del ME, a través de experimentos de detección directa de partículas hipotéticas, sino también para proponer nuevos observables para la detección indirecta de NF que pueda llegar a haber pasado inadvertida hasta la fecha. Esta tesis presenta una serie de estudios fenomológicos que cubren separadamente las dos líneas de detección de NF anteriormente mencionadas. En el marco de la detección indirecta, presentamos un estudio de la producción de cuatro tops en el LHC como posible prueba de NF liviana y top-fílica. Aprovechando la oportunidad dada al quark top en numeras extensiones del ME como posible mediador a sectores desconocidos de partículas, por ser la partícula más pesada hasta ahora encontrada, estudiamos el impacto en la producción de cuatro tops de la presencia de posibles nuevas partículas de espín 0, 1 o 2, cuyas masas están por debajo de la producción de pares de tops. Proponemos una serie de nuevos observables que identifican y distinguen entre dichas señales, que deben ser tenidos en cuenta en las estrategias venideras para la medición de cuatro tops en el LHC. Por otro lado, en el marco de los experimentos de detección directa, nos centramos en el bosón Z, un mediador hipotético que aparece en una gran variedad de modelos de NF y teniendo en cuenta el número de búsquedas de Z que se han llevado a cabo en el LHC, presentamos un software, Z–explorer para probar fácilmente modelos de Z contra todos estos resultados para canales visibles. Simplemente proporcionando acoplamientos y anchos de decaimiento (o alternativamente, la sección eficaz de producción y la tasa de decaimiento para cada canal visible), Z explorer permite probar un modelo dado, determinando el canal más sensible para la exclusión/detección de un Z dado dentro el espacio de parámetros de NF, erigiéndose como una herramienta fenomológica de enlace entre teoría y experimentos. Finalmente, y para incluir la fenomenología que proporciona la interacción con otros sectores escondidos, presentamos además una actualización del software, Z-explorer 2.0, que incluye las búsquedas en el LHC de bosones Z acoplando a materia oscura fermiónica. A través de esta propuesta, también exponemos los principales aspectos de la fenomenología de nuevas partículas decayendo en especies invisibles.
Over the last few years, the advances made in the experimental field of particle physics, associated with the achievements at the Large Hadron Collider (or LHC), have allowed testing like never before. to the Standard Model (ME). The predictions of this model have been measured and validated with unprecedented precision, and yet the number of unexplained phenomena and questions about its structure continue to show it as an effective theory up to the energies explored. The search for New Physics (NF) is one of the key programs at the LHC, but in the face of results that do not give clues about the way forward, phenomenological proposals become more relevant. These proposals may be fundamental in the coming years, not only to chart new search paths and to set limits to theories beyond the ME, through direct detection experiments of hypothetical particles, but also to propose new observables for indirect detection. of NF that may have gone unnoticed to date. This thesis presents a series of phenomological studies that separately cover the two lines of NF detection mentioned above. In the framework of indirect detection, we present a study of the production of four tops at the LHC as a possible test of light and top-philic NF. Taking advantage of the opportunity given to the top quark in numerous extensions of the ME as a possible mediator to unknown sectors of particles, as it is the heaviest particle so far found, we study the impact on the production of four tops of the presence of possible new particles of spin 0 , 1 or 2, whose masses are below the production of pairs of tops. We propose a series of new observables that identify and distinguish between these signals, which must be taken into account in upcoming strategies for measuring four tops at the LHC. On the other hand, in the framework of direct detection experiments, we focus on the Z boson, a hypothetical mediator that appears in a wide variety of NF models and taking into account the number of Z searches that have been carried out at the LHC, we introduced a software, Z–explorer, to easily test Z models against all of these results for visible channels. By simply providing couplings and decay widths (or alternatively, the production cross section and decay rate for each visible channel), Z explorer allows a given model to be tested, determining the most sensitive channel for exclusion/detection of a given Z within the NF parameter space, establishing itself as a phenomological tool for linking theory and experiments. Finally, and to include the phenomenology provided by the interaction with other hidden sectors, we also present a software update, Z-explorer 2.0, which includes searches at the LHC for Z bosons coupling to fermionic dark matter. Through this proposal,we also expose the main aspects of the phenomenology of new particles decaying into invisible species.
Over the last few years, the advances made in the experimental field of particle physics, associated with the achievements at the Large Hadron Collider (or LHC), have allowed testing like never before. to the Standard Model (ME). The predictions of this model have been measured and validated with unprecedented precision, and yet the number of unexplained phenomena and questions about its structure continue to show it as an effective theory up to the energies explored. The search for New Physics (NF) is one of the key programs at the LHC, but in the face of results that do not give clues about the way forward, phenomenological proposals become more relevant. These proposals may be fundamental in the coming years, not only to chart new search paths and to set limits to theories beyond the ME, through direct detection experiments of hypothetical particles, but also to propose new observables for indirect detection. of NF that may have gone unnoticed to date. This thesis presents a series of phenomological studies that separately cover the two lines of NF detection mentioned above. In the framework of indirect detection, we present a study of the production of four tops at the LHC as a possible test of light and top-philic NF. Taking advantage of the opportunity given to the top quark in numerous extensions of the ME as a possible mediator to unknown sectors of particles, as it is the heaviest particle so far found, we study the impact on the production of four tops of the presence of possible new particles of spin 0 , 1 or 2, whose masses are below the production of pairs of tops. We propose a series of new observables that identify and distinguish between these signals, which must be taken into account in upcoming strategies for measuring four tops at the LHC. On the other hand, in the framework of direct detection experiments, we focus on the Z boson, a hypothetical mediator that appears in a wide variety of NF models and taking into account the number of Z searches that have been carried out at the LHC, we introduced a software, Z–explorer, to easily test Z models against all of these results for visible channels. By simply providing couplings and decay widths (or alternatively, the production cross section and decay rate for each visible channel), Z explorer allows a given model to be tested, determining the most sensitive channel for exclusion/detection of a given Z within the NF parameter space, establishing itself as a phenomological tool for linking theory and experiments. Finally, and to include the phenomenology provided by the interaction with other hidden sectors, we also present a software update, Z-explorer 2.0, which includes searches at the LHC for Z bosons coupling to fermionic dark matter. Through this proposal,we also expose the main aspects of the phenomenology of new particles decaying into invisible species.