  In this thesis we will address three different phenomena related to neutrino
physics: mass models, detection of the cosmic neutrino background and the
neutrino background in Dark Matter searches, considering the different
characteristics in each case. In the study of neutrino mass models, we will
consider models for both Majorana and Dirac neutrinos; specifically, we will
probe the neutrinophilic two-Higgs-doublet model. Regarding the detection of
relic neutrinos, we will analyse the consequences of the existence of physics
beyond the Standard Model in the capture rate by tritium. Finally, we will
scrutinize the impact of neutrinos in Direct Detection searches of Weakly
Interacting Massive Particles (WIMP) including Standard Model plus additional
interactions in the form of simplified models.
