Sterile neutrinos in the early Universe
- 9 december 2015
2311 GJ Leiden
Promotor(s): Alexey Boyarsky
Co-promotor(s): Ana Achucarro
Although we know that the Standard Model (SM) of elementary particles and their interactions successfully describes the Universe up to the smallest known scales, there exists a number of observational phenomena, which do not find explanation in the framework of this theory. Among these fundamental problems are Neutrino Oscillations, Dark Matter and the Baryon Asymmetry of the Universe. In this thesis, the so-called Neutrino Minimal Standard Model (nuMSM) is studied, a minimalistic extension of the Standard Model, which can explain all these three phenomena simultaneously, by adding only three right-handed neutrinos to the known three left-handed neutrinos.
We show that the two heavier sterile neutrinos with masses below the mass of pi-meson could have been present in such large amounts in the early Universe that they spoil the otherwise excellent agreement between the Standard-Model prediction of light atomic nuclei production and the astrophysical observations. In this way, masses of sterile neutrinos are excluded from below, which reduces the potentially interesting parameter space for future accelerator searches, like in the planned experiment SHiP (Search for Hidden Particles) at CERN. Another question studied in the thesis, is the production of magnetic fields, which is triggered by presence of sterile neutrinos in the hot and dense environment of the early Universe.
Inès van Arkel, Adviseur wetenschapscommunicatie
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