Consiglio, Rosa (2016) Sterile Neutrino in Cosmology. [Tesi di dottorato]


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Item Type: Tesi di dottorato
Lingua: English
Title: Sterile Neutrino in Cosmology
Date: 30 March 2016
Number of Pages: 144
Institution: Università degli Studi di Napoli Federico II
Department: Fisica
Scuola di dottorato: Scienze fisiche
Dottorato: Fisica fondamentale ed applicata
Ciclo di dottorato: 28
Coordinatore del Corso di dottorato:
Mangano, GianpieroUNSPECIFIED
Date: 30 March 2016
Number of Pages: 144
Uncontrolled Keywords: cosmology, sterile neutrino, dark matter
Settori scientifico-disciplinari del MIUR: Area 02 - Scienze fisiche > FIS/02 - Fisica teorica, modelli e metodi matematici
Date Deposited: 14 Apr 2016 20:53
Last Modified: 31 Oct 2016 09:46


Sterile neutrino, in addition to providing neutrino mass generation, depending on its mass scale, may have many important cosmological implications. eV sterile neutrinos may explain the dark radiation problem (i.e. additional relativistic density quantified by the effective number of neutrino species) and the experimental data of short baseline experiments, a KeV sterile neutrino may be a warm dark matter candidate and furthermore sterile neutrinos may also provide baryogenesis through leptogenesis. The main way of obtaining a significant abundance of sterile neutrinos is through their mixing and oscillations with the active neutrinos. Active-sterile neutrino oscillations may have considerable effects in the early universe. One or more than one sterile neutrino may exist avoiding the cosmological constraints only by suppressing the thermalization of sterile neutrinos in the early universe and/or by considering non-standard cosmological theories. Two different mechanisms to suppress the sterile neutrinos thermalization and their eventual large production have been studied. In particular, the existence of neutrino asymmetries or the introduction of secret interactions among sterile neutrinos. The existence of sterile neutrinos not fully thermalized with the active species in the early universe in principle is compatible with Big-Bang Nucleosynthesis data. It is also compatible with cosmological measurements of the Cosmic Microwave Background and Large-Scale Structures, if the neutrino masses do not exceed 1 eV. However, the scenarios of secret self-interactions studied so far are not suffcient to reconcile sterile neutrinos with cosmology. The new picture, that we will introduce consists in assuming the same secret interactions with a light pseudoscalar as the source of sterile neutrino production by oscillations (when they involve active species) and, in addition, along with the self-interactions we will also consider interactions between sterile neutrino and pseudoscalar particle in the sterile sector.

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