Browsing by Author "Santoni, Alessandro"

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    Delving into the phenomenology of very special relativity: from subatomic particles to binary stars
    (2024) Santoni, Alessandro; Muñoz Tavera, Enrique; Koch, Benjamin; Pontificia Universidad Católica de Chile. Facultad de Física
    En esta tesis, se investigan las implicaciones de las teorías de violación de Lorentz (LV), enfocándose en Very Special Relativity (VSR) y sus consecuencias fenomenológicas. Presentada inicialmente como un mecanismo alternativo para las masas de los neutrinos, VSR se ha convertido en una parte significativa del marco general de la LV, distinguida por su estructura de grupo y la presencia de operadores no locales.Después de una introducción exhaustiva a los principios de la LV y VSR, presentamos sus modificaciones a la ecuación de Dirac. Una parte significativa de la tesis está dedicada al desarrollo de un formalismo Hamiltoniano dentro del contexto de VSR, abordando sus no-localidades. Este enfoque se extiende al límite no relativista, conectándolo al esquema de Schrödinger.Luego establecemos límites superiores en los parámetros de VSR, examinando sus correcciones a una amplia gama de sistemas y escenarios físicos, como los niveles de Landau de partículas cargadas, el factor g de los electrones, el espectro de energía de neutrones ultrafríos en el campo gravitatorio terrestre, y la emisión gravitacional de estrellas binarias. Este último análisis nos llevó a la construcción de una teoría de campo en VSR para partículas de espín-2, que resultó acomodar una masa del gravitón gauge-invariante.Mediante este estudio, conectamos varias predicciones teóricas con datos experimentales, allanando el camino para futuras exploraciones en teorías de LV y evidenciando su potencial para abordar preguntas no resueltas en la física moderna.
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    Graviton mass bounds in very special relativity from binary pulsar's gravitational waves
    (2023) Santoni, Alessandro; Alfaro, Jorge; Soto, Alex
    In this work we study the gravitational radiation produced by a Keplerian binary system within the context of very special linear gravity (VSLG), a novel theory of linearized gravity in the framework of very special relativity allowing for a gauge-invariant mass mg of the graviton. For this task, we exploit effective field theory's techniques, which require, among others, the calculation of the squared amplitude of the emission process and therefore the polarization sum for VSLG gravitons. Working in the radiation zone and using the standard energy-momentum tensor's expression for Keplerian binaries, we derive and study the properties of the VSLG energy-loss and period-decrease rates, also verifying they reduce to the correct General Relativity limit when sending m(g) -> 0. Finally, using astronomical data from the Hulse-Taylor binary and the double pulsar J0737-3039, we obtain an upper bound on the VSLG graviton mass of mg similar to 10(-21) eV that, while being comparable to bounds obtained in this same way for other massive gravity models, is still weaker than the kinematical bound similar to 10(-22) eV obtained from the combined observation of the astronomical events GW170817 and GRB170817A, which should still hold in VSLG.
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    Very special linear gravity: A gauge-invariant graviton mass
    (2022) Alfaro, Jorge; Santoni, Alessandro
    Linearized gravity in the Very Special Relativity (VSR) framework is considered. We prove that this theory allows for a non-zero graviton mass m(g) without breaking gauge invariance nor modifying the relativistic dispersion relation. We find the analytic solution for the new equations of motion in our gauge choice, verifying as expected the existence of only two physical degrees of freedom. Finally, through the geodesic deviation equation, we confront some results for classic gravitational waves (GW) with the VSR ones: we see that the ratios between VSR effects and classical ones are proportional to (m(g)/E)(2), E being the energy of a graviton in the GW. For GW detectable by the interferometers LIGO and VIRGO this ratio is at most 10(-20). However, for GW in the lower frequency range of future detectors, like LISA, the ratio increases significantly to 10(-)(10), that combined with the anisotropic nature of VSR phenomena may lead to observable effects. (C) 2022 The Authors. Published by Elsevier B.V.