Sterile Neutrino Dark Matter PDF Download

Non-standard interactions (NSI) between active neutrinos (neutrinos belonging to the Standard Model) have the potential to modify the production of a fourth type of keV-scale mass neutrino (called "sterile"), due to active-sterile neutrino oscillations in the early Universe, a process known as the Dodelson-Widrow mechanism (DW). Through this modified DW mechanism, enough sterile neutrinos could be produced to account for the whole of the dark matter. This type of dark matter production occurred before big bang nucleosynthesis (BBN), an era just before the temperature of the Universe settled to 5 MeV, which is currently unknown. Thus, this type of dark matter production can be explored with different pre-BBN cosmological models. Taking into consideration the uncertainties in the pre-BBN cosmology besides the effects of NSI, we may identify a viable parameter space for sterile neutrino searches allowed by astrophysical limits and assess their effect on the range of mixing angles for keV-scale mass sterile neutrino dark matter. Detection of a sterile neutrino could provide insight into the pre-BBN era of the Universe. We find that the combined uncertainties in the early Universe cosmologies, as well as in the active neutrino interactions, significantly expand the allowed parameter space for sterile neutrinos that could constitute the whole of the dark matter. This thesis work will be published in a paper with the same title by C. Chichiri, G. Gelmini, P. Lu and V. Takhistov, already posted as a preprint in the arXiv,e-Print: 2.111.04087[hep-ph], and submitted for publication to the Journal of Cosmology and Astroparticle Physics (JCAP).