NAGIOS: RODERIC FUNCIONANDO

Testing neutrino physics and dark radiation properties with cosmological measurements

Repositori DSpace/Manakin

IMPORTANT: Aquest repositori està en una versió antiga des del 3/12/2023. La nova instal.lació está en https://roderic.uv.es/

Testing neutrino physics and dark radiation properties with cosmological measurements

Mostra el registre parcial de l'element

dc.contributor.advisor Mena Requejo, Olga
dc.contributor.author Giusarma, Elena
dc.contributor.other Departament de Fisica Teòrica es_ES
dc.date.accessioned 2013-10-04T12:29:08Z
dc.date.available 2013-10-05T06:10:03Z
dc.date.issued 2013
dc.date.submitted 11-10-2013 es_ES
dc.identifier.uri http://hdl.handle.net/10550/30242
dc.description.abstract El Modelo Estándard de partículas fundamentales asume que hay tres especies de neutrinos sin masa que interactúan a través de la fuerza débil. Durante los últimos años, los experimentos con neutrinos solares, atmosférico, aquellos de reactores y aceleradores han aportado pruebas sólidas de la existencia de oscilaciones del neutrino. Esto implica que los neutrinos tienen masa. Sin embargo, los experimentos de oscilaciones determinan sólo la diferencias relativas de las masas de los neutrinos; la escala absoluta de masas puede determinarse mediante datos cosmológico. Las masas de los neutrinos afectan los distintos observables cosmológicos, in particular, a la evolución de las perturbaciones de materia, a la formación de estructuras y a la CMB (Cosmic Microwave Background). La tesis se centra en el estudio de cómo poner cotas a los parámetros cosmologicos, en particular de los neutrinos, que describen la imagen de nuestro universo, aprovechando de los nuevos datos cosmológicos. es_ES
dc.description.abstract In the Standard Model of elementary particles, there are three massless neutrino species that interact through the weak force. During the last several years, experiments involving solar, atmospheric, reactor and accelerator neutrinos have adduced robust evidence for the existence of neutrino oscillations, implying that neutrinos have masses. Oscillation experiments only provide bounds on the neutrino mass squared differences while cosmology supply a tool to study the absolute scale of neutrino masses. In the early universe, the standard model neutrinos are in thermal equilibrium at temperatures larger than about a MeV, after which they decouple when they are still relativistic, leaving a distribution of relic neutrinos that contribute to the energy density of the universe. These neutrinos affect the expansion rate of the universe and change the epoch of matter-radiation equality, leaving an imprint on the Cosmic Microwave Background (CMB) anisotropies and on structure formation. After becoming non-relativistic, they suppress the growth of matter density fluctuations and galaxy clustering. These observations have been used to place new constraints on neutrino physics with an upper bound on the sum of neutrino masses m <0.6 eV at 95% CL. This bound depends on the combination of data sets and on the cosmological model. The simplest explanations of neutrino mass require the existence of right handed, singlet neutrino states. However, there is no fundamental symmetry in the standard model that fixes the number of such sterile states. This means that there may be sterile neutrinos in nature. Cosmological data provide also the possibility of a measurement of the relativistic energy density of the universe in terms of the effective number of neutrinos. If the effective number of neutrinos Neff is larger than the Standard Model prediction of Neff = 3.046 at the Big Bang Nucleosynthesis (BBN) era, the relativistic degrees of freedom, and, consequently, the Hubble expansion rate will also be larger causing weak interactions to become un effective earlier. This will lead to a larger neutronto-proton ratio and will change the standard BBN predictions for light element abundances. My tesis is focused on the study of cosmological neutrino constraints using the most recent and available cosmological data. In particular I explore the bounds on the active and sterile neutrino masses as well as on the number of steriles neutrino species within the "CDM cosmological scenario as well as in other extended scenarios. en_US
dc.format.extent 163 p. es_ES
dc.language.iso en es_ES
dc.subject cosmology es_ES
dc.title Testing neutrino physics and dark radiation properties with cosmological measurements es_ES
dc.type doctoral thesis es_ES
dc.subject.unesco UNESCO::ASTRONOMÍA Y ASTROFÍSICA es_ES
dc.subject.unesco UNESCO::FÍSICA es_ES
dc.embargo.terms 0 days es_ES

Visualització       (6.405Mb)

Aquest element apareix en la col·lecció o col·leccions següent(s)

Mostra el registre parcial de l'element

Cerca a RODERIC

Cerca avançada

Visualitza

Estadístiques