Phenomenology of the Sterile Neutrinos

TL;DR

This thesis explores the phenomenology of sterile neutrinos, examining their existence, interactions, and implications across various experimental and theoretical frameworks in neutrino physics.

Contribution

It provides a comprehensive analysis of sterile neutrino phenomenology, including experimental constraints, model equivalences, and theoretical limitations in neutrino mass explanations.

Findings

Evidence for a light sterile neutrino in 3+1 scenario from reactor data

Equivalence established between Kaluza Klein modes and sterile neutrinos in extra dimension models

Minimal 2-Higgs-Doublet-Model cannot account for small neutrino masses

Abstract

In this thesis we investigate several topics in neutrino physics, with an em- phasis on the phenomenology of the sterile neutrinos. We study the existence of a light sterile neutrino within the so called 3+1 scenario using the data of the medium baseline reactor experiments. We will also probe the parameters of the Large Extra Dimension model with the high energy atmospheric data of the IceCube experiment, and will find an equivalence between the Kaluza Klein modes and the sterile neutrinos. We will study the secret interaction of the ster- ile neutrinos which is proposed to solve the tension between cosmology and the sterile neutrino hypothesis. In addition to these, we will show that a minimal 2-Higgs-Doublet-Model extended with a U(1) or Z_2 symmetry cannot explain the smallness of the neutrino masses.